DOCSLIB.ORG

Sequential Induction of Fur-Regulated Genes in Response to Iron Limitation in Bacillus Subtilis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Sequential Induction of Fur-Regulated Genes in Response to Iron Limitation in Bacillus Subtilis Sequential induction of Fur-regulated genes in response to iron limitation in Bacillus subtilis Hualiang Pia and John D. Helmanna,1 aDepartment of Microbiology, Cornell University, Ithaca, NY 14853-8101 Edited by Alan D. Grossman, Massachusetts Institute of Technology, Cambridge, MA, and approved October 11, 2017 (received for review July 21, 2017) Bacterial cells modulate transcription in response to changes in iron (FeuABC-YusV), both of which are under Fur regulation (5, 7, 8). availability. The ferric uptake regulator (Fur) senses intracellular iron A phosphopantetheinyl transferase (encoded by sfp)isalsorequired availability and plays a central role in maintaining iron homeostasis for BB biosynthesis (9, 10). Most laboratory strains of B. subtilis + in Bacillus subtilis. Here we utilized FrvA, a high-affinity Fe2 efflux [those derived from the legacy strain B. subtilis 168 (11)] carry an sfp transporter from Listeria monocytogenes, as an inducible genetic null mutation (sfp0) (9, 10) and can only produce the BB precursor tool to deplete intracellular iron. We then characterized the re- 2,3-dihydroxybenzoic acid (DHBA) and its glycine conjugate sponses of the Fur, FsrA, and PerR regulons as cells transition from (DHBG) [collectively assigned as DHB(G)]. The DHB(G) com- + + iron sufficiency to deficiency. Our results indicate that the Fur reg- pounds bind to Fe3 with modest affinity, while BB binds to Fe3 ulon is derepressed in three distinct waves. First, uptake systems for with very high affinity (7, 12). BB uptake shares the same pathway elemental iron (efeUOB), ferric citrate (fecCDEF), and petrobactin as enterobactin (FeuABC-YusV) (8) and is under two levels of (fpbNOPQ) are induced to prevent iron deficiency. Second, B. subtilis regulation: iron-dependent repression by Fur and substrate-specific synthesizes its own siderophore bacillibactin (dhbACEBF)andturns activation by Btr (bacillibactin transport regulator), an AraC family on bacillibactin (feuABC) and hydroxamate siderophore (fhuBCGD) transcriptional activator (13, 14). In addition to its prototypic role as + uptake systems to scavenge iron from the environment and flavo- an Fe2 -sensing repressor, emerging evidence indicates that in some + doxins (ykuNOP) to replace ferredoxins. Third, as iron levels decline cases, apo-Fur (without its coregulator Fe2 -bound) also binds further, an “iron-sparing” response (fsrA, fbpAB,andfbpC)isin- DNA, and both forms of Fur may also function as transcriptional duced to block the translation of abundant iron-utilizing proteins activators (15–17). and thereby permit the most essential iron-dependent enzymes ac- To adapt to iron limitation, bacteria also reconfigure their pro- cess to the limited iron pools. ChIP experiments demonstrate that teome to reduce synthesis of abundant, iron-utilizing proteins that in vivo occupancy of Fur correlates with derepression of each op- are not essential for growth (an “iron-sparing” response), and they eron, and the graded response observed here results, at least in part, express alternative, iron-independent versions of some proteins. from higher-affinity binding of Fur to the “late”-induced genes. Together, these responses enable the cell to prioritize utilization of iron (13, 18, 19). In B. subtilis, Fur regulates FsrA, a noncoding Fur regulon | iron limitation | graded response | iron-sparing response Fur-regulated small RNA, which mediates the iron-sparing re- sponse with the help of three putative RNA chaperones (FbpABC) ron is indispensable for cell growth and survival for most (13, 19). FsrA and its coregulators block the translation of low- Ibacteria. In many natural environments, particularly under priority iron-utilizing enzymes such as aconitase and succinate neutral pH and aerobic conditions, iron limitation is a big chal- dehydrogenase and enable high-priority iron-dependent proteins to lenge for bacteria due to the extremely low solubility and bio- utilize the limited iron (13, 19). In addition, cells may substitute + availability of the Fe3 ion. However, iron can also be toxic to iron-independent flavodoxin for ferrodoxin, an abundant iron– cells when present in excess due to its participation in Fenton sulfur protein involved in electron transfer reactions. Expression of chemistry, which generates reactive oxygen radicals resulting in flavodoxins (YkuNOP) is under regulation of Fur (5, 20). macromolecular damage and cell death (1, 2). Therefore, bac- Another transcriptional regulator that plays an important role teria require regulatory systems to maintain iron homeostasis. in B. subtilis iron homeostasis is PerR, which modulates the The ferric uptake regulator (Fur) senses intracellular iron levels and plays a critical role in bacterial iron homeostasis by virtue of Significance its ability to regulate transcription of genes involved in iron up- take, storage, and efflux (3, 4). Fur is a key regulator of bacterial iron homeostasis and regulates The Fur regulon has been well characterized in Bacillus subtilis the derepression of iron acquisition systems when iron is limited. and includes more than 50 genes, many of which are implicated However, it is unclear whether Fur-regulated genes are dere- in iron uptake, endogenous siderophore (bacillibactin) synthesis pressed coordinately or in a sequential manner. Here, we de- and uptake, and xenosiderophore uptake (siderophore made by scribe a graded response for the Bacillus subtilis Fur regulon as other organisms) (5). Under iron-sufficient conditions, Fur binds the intracellular iron pool is gradually depleted. Three distinct 2+ to Fe in the cytosol, and the resultant holo-Fur binds to its sets of genes are sequentially expressed, and the induction order target DNA operators and functions as a repressor; under iron- can be explained, at least in part, by differences in Fur affinity to limited conditions, apo-Fur dissociates from DNA, and the re- its target operator sites. These results provide insights into the pression by Fur is relieved. Derepression of the Fur regulon distinct roles of Fur target genes and contribute to our under- leads to expression of numerous iron uptake systems to scavenge standing of bacterial metalloregulatory systems. iron and adapt to iron deficiency. These include transporters for the import of elemental iron (EfeUOB), ferric citrate (YfmCDEF, Author contributions: H.P. and J.D.H. designed research; H.P. performed research; H.P. renamed as FecCDEF to reflect their physiological role in ferric and J.D.H. analyzed data; and H.P. and J.D.H. wrote the paper. citrate import), hydroxamate siderophores (ferrioxamine and The authors declare no conflict of interest. ferrichrome) (FhuBCGD-YxeB), and petrobactin (YclNOPQ, This article is a PNAS Direct Submission. renamed as FpbNOPQ to reflect their role in ferric petrobactin Published under the PNAS license. 1 import) (6). To whom correspondence should be addressed. Email: [email protected]. GENETICS In addition, B. subtilis synthesizes its own siderophore, This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. bacillibactin (BB) (DhbACEBF), and a cognate uptake system 1073/pnas.1713008114/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1713008114 PNAS | November 28, 2017 | vol. 114 | no. 48 | 12785–12790 Downloaded by guest on October 2, 2021 adaptive response to peroxide stress, including peroxide detoxi- fication, heme biosynthesis, and iron storage genes (21–26). PerR also regulates pfeT,aP1B4-type ATPase recently charac- + terized as an Fe2 efflux transporter (27). Expression of pfeT is induced under two conditions, oxidative stress and excess iron (27). A homolog of PfeT in Listeria monocytogenes, FrvA, has + been identified as a high-affinity Fe2 exporter, and its expres- sion imposes severe iron limitation that leads to derepression of the Fur and PerR regulons in B. subtilis (28). In this study, we utilized L. monocytogenes FrvA as an in- ducible genetic tool to deplete intracellular iron. By monitoring the transcription of Fur-regulated genes as cells transition from iron sufficiency to deficiency we determined that the Fur regulon is derepressed in three distinguishable waves. The first wave Fig. 1. Induction of L. monocytogenes FrvA imposes iron deprivation and comprises uptake systems for elemental iron (efeUOB), ferric inhibits cell growth of B. subtilis. (A) Levels of intracellular metals (Fe, Mn, and citrate (fecCDEF), and petrobactin (fpbNOPQ); in the second Co) were monitored for 3 h after 1 mM IPTG addition by inductively coupled plasma mass spectrometry (ICP-MS). The total concentration of ions was wave, B. subtilis synthesizes its own siderophore bacillibactin expressed as μgionpergramofprotein(mean± SD; n = 3). Significant dif- (dhbACEBF) and turns on bacillibactin uptake (feuABC) along ferences between WT and induced Pspac-frvA cells are determined by two- with hydroxamate siderophore uptake (fhuBCGD) and fla- tailed t test as indicated: *P < 0.01. (B) Representative growth curves of the vodoxins (ykuNOP); last, as iron levels decrease further, the iron- same strains as A in LB medium amended with 10 μMFeSO4. For IPTG-treated ∼ sparing response (fsrA, fbpAB, and fbpC) is induced to prioritize cells, 1 mM IPTG was added to cell culture when OD600 reaches 0.25. Exper- iron utilization. Furthermore, the stepwise induction of Fur- iments were performed at least three times with three biological replicates. regulated genes correlates with operator occupancy in vivo and can be explained, at least in
Load more

Recommended publications
  • Production of Bacillibactin Siderophore from Soil Bacteria, Bacillus Subtilis: a Bioinoculant Enhances Plant Growth in Arachis Hypogaea L
    Advances in Biological Sciences Research, volume 13 Proceedings of the International Seminar on Promoting Local Resources for Sustainable Agriculture and Development (ISPLRSAD 2020) Production of Bacillibactin Siderophore from Soil Bacteria, Bacillus subtilis: A Bioinoculant Enhances Plant Growth in Arachis hypogaea L. Through Elevated Uptake of Nutrients Lalitha S1* and Nithyapriya S1 1*Department of Botany, Periyar University, Salem 636011.Tamil Nadu, India, 1 Department of Botany, Padmavani Arts and Science Collage for women, Salem 636011.Tamil Nadu, India. * Corresponding author Email- [email protected] ABSTRACT Siderophores are iron chelator low molecular weight secondary metabolite produced by microorganisms found in limited iron environment. In this study, a bacterium capable of secreting siderophores was isolated from the iron deficiency rhizosphere agriculture soil from Salem district, Tamil Nadu, India. The isolate was identified as Bacillus subtilis(LSBS2) based on biochemical characteristics and 16S rRNA gene sequences analysis. The siderophores production ability of the strain was evaluated qualitatively and quantitatively through Chrome Azural S assay. The TLC analysis of the LSBS2extract developed brown colour spots indicating catacholate type of siderosphore of isolate had the ability to produce 20 mg L-1 of siderophores in liquid medium. Further, the siderophores was partially purified and identified as bacillibactin type using HPLC, FTIR and the bacillibactin structure was confirmed by 2D-NMR analysis. Furthermore, a field experiment was conducted with Arachis hypogaea to assess the inoculation effect of LSBS2 on plant growth and other physico-chemical parameters. Inoculation of LSBS2 increased plant biomass, pigment content, nutrients, Iron content and oil content than the uninoculated control. The present result suggested that the occurrence of bacillibactin type siderophores in strain LSBS2 play a key role in iron chelation and favors the healthy growth of Sesamum indicum.
    [Show full text]
  • Characterization of a Bacillus Subtilis Transporter for Petrobactin, an Anthrax Stealth Siderophore
    Characterization of a Bacillus subtilis transporter for petrobactin, an anthrax stealth siderophore Anna M. Zawadzkaa, Youngchang Kimb,1, Natalia Maltsevab, Rita Nichiporuka, Yao Fanb, Andrzej Joachimiakb, and Kenneth N. Raymonda aDepartment of Chemistry, University of California, Berkeley, CA 94720-1460; and bBiosciences Division, Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL 60439 Edited by Joan Selverstone Valentine, University of California, Los Angeles, CA, and approved October 13, 2009 (received for review May 20, 2009) Iron deprivation activates the expression of components of the aspects of siderophore synthesis, transport, and regulation (4–8). B. siderophore-mediated iron acquisition systems in Bacillus subtilis, subtilis produces bacillibactin (BB), a 2,3-dihydroxybenzoyl-Gly- including not only the synthesis and uptake of its siderophore Thr trilactone siderophore (Fig. 1) (9), and expresses a BB-specific bacillibactin but also expression of multiple ABC transporters for iron ABC transporter FeuABC-YusV (6). Additionally, transporters scavenging using xenosiderophores. The yclNOPQ operon is shown to specific for exogenous siderophores, including ferric citrate, fer- encode the complete transporter for petrobactin (PB), a photoreactive richromes (Fch), ferrioxamines, and citrate-based hydroxamates, 3,4-catecholate siderophore produced by many members of the B. have been identified (7, 10). Our previous studies determined that cereus group, including B. anthracis. Isogenic disruption mutants in B. subtilis can also use petrobactin (PB) for iron acquisition via a the yclNOPQ transporter, including permease YclN, ATPase YclP, and receptor different from the BB transporter (11). a substrate-binding protein YclQ, are unable to use either PB or the First found as a siderophore produced by marine bacteria (12), photoproduct of FePB (FePB␯) for iron delivery and growth, in contrast PB is also synthesized by members of the B.
    [Show full text]
  • Characterization of Siderophore-Host Interactions
    Characterization of Siderophore-Host Interactions Emma Worden-Sapper Thesis Defense Date April 8, 2019 Thesis Advisor: Min Han, MCDB Honors Council Representative: Christy Fillman, MCDB Other Committee Member: Stephanie Renfrow, EBIO Abstract The role of the gut microbiome in influencing human health has received increasing attention in the past decade, with many of the interactions between symbiont and host being elucidated. A recent study found that the siderophore enterobactin, secreted by E. coli to scavenge iron from its environment, is an essential metabolite for Caenorhabditis elegans (C. elegans) development. The benefit of enterobactin, which appears to be conserved in mammals, carries potential for treating iron deficiency disorder. This thesis focuses on characterizing the nature of the interaction of C. elegans with siderophores other than enterobactin, to assess the uniqueness of the benefit enterobactin conveys to the host. By performing a series of assays with C. elegans, I provide evidence that yersiniabactin, ornibactin, and bacillibactin do not promote C. elegans growth, implying that these siderophores do not convey a benefit similar to enterobactin. 1. Introduction The increasing attention towards the health impacts of human microbial residents (the microbiome) has produced many surprising contradictions to the previous notions of the nature of host-microbe interactions. The microbiome has been found to impact mental health (Dinan and Cryan 2017; Hsiao et al. 2013; Sharon et al. 2014), the development of the immune system (Brestoff and Artis 2013; Hooper, Littman, and Macpherson 2012; Ellermann and Arthur 2017), and metabolism (Sharon et al. 2014; Ellermann and Arthur 2017) among many other physiological functions. One of these previous notions, that bacterial residents of the gastrointestinal (GI) tract “steal” iron from their hosts (Ellermann and Arthur 2017), has recently been challenged (Qi and Han 2018), suggesting a new interaction between host and resident that may carry implications for anemia treatments (Eschner 2018).
    [Show full text]
  • Analysis of Virulence-Associated Petrobactin Reacquisition in Bacillus Anthracis
    Analysis of Virulence-Associated Petrobactin Reacquisition in Bacillus anthracis by Shandee Dawn Dixon A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Microbiology and Immunology) in The University of Michigan 2013 Doctoral Committee: Professor Philip C. Hanna, Chair Professor Carol A. Fierke Associate Professor Maria B. Sandkvist Professor David H. Sherman The Bacillus anthracis Petrobactin ATP-Binding Cassette (ABC) Import System ©Shandee D. Dixon 2013 DEDICATION For my Family ii PREFACE This written dissertation summarizes the labor and thought invested in my graduate studies to develop a better understanding of how Bacillus anthracis reacquires the vital siderophore petrobactin back into the cytoplasm after sequestering iron from its host. The identification of this system and the elucidation of the mechanisms involved in the reacquisition of iron-bound petrobactin will greatly improve our current knowledge of Bacillus anthracis pathogenesis. This body of work is divided into four chapters. Chapter 1 introduces the general importance of iron in microbial biology and aspects of iron acquisition in Bacillus anthracis. A n emphasis is placed on c urrent research surrounding the virulence- associated siderophore petrobactin and introduces the uptake mechanisms employed by bacteria to reacquire iron-bound siderophores. Additionally, Chapter 1 describes work I performed along with my colleagues during my first year in the Hanna laboratory which provides the first description of the only receptor protein required for the reacquisition of petrobactin. This research has been published as an article in the journal Molecular Microbiology (Carlson PE Jr, Dixon SD, Janes BK, Carr KA, Nusca TD, Anderson EC, Keene SE, Sherman DH, and Hanna PC 2008.
    [Show full text]
  • Coordination Chemistry of Microbial Iron Transport Kenneth N
    This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Article pubs.acs.org/accounts Coordination Chemistry of Microbial Iron Transport Kenneth N. Raymond,* Benjamin E. Allred, and Allyson K. Sia Department of Chemistry, University of California, Berkeley, California 94720-1460, United States CONSPECTUS: This Account focuses on the coordination chemistry of the microbial iron chelators called siderophores. The initial research (early 1970s) focused on simple analogs of siderophores, which included hydroxamate, catecholate, or hydrox- ycarboxylate ligands. The subsequent work increasingly focused on the transport of siderophores and their microbial iron transport. Since these are pseudo-octahedral complexes often composed of bidentate ligands, there is chirality at the metal center that in principle is independent of the ligand chirality. It has been shown in many cases that chiral recognition of the complex occurs. Many techniques have been used to elucidate the iron uptake processes in both Gram-positive (single membrane) and Gram-negative (double membrane) bacteria. These have included the use of radioactive labels (of ligand, metal, or both), kinetically inert metal complexes, and Mössbauer spectroscopy. In general, siderophore recognition and transport involves receptors that recognize the metal chelate portion of the iron−siderophore complex. A second, to date less commonly found, mechanism called the siderophore shuttle involves the receptor binding an apo- siderophore. Since one of the primary ways that microbes compete with each other for iron stores is the strength of their competing siderophore complexes, it became important early on to characterize the solution thermodynamics of these species.
    [Show full text]
  • Amide Compound Synthesis by Adenylation Domain of Bacillibactin Synthetase
    The Journal of Antibiotics (2017) 70, 435–442 & 2017 Japan Antibiotics Research Association All rights reserved 0021-8820/17 www.nature.com/ja ORIGINAL ARTICLE Amide compound synthesis by adenylation domain of bacillibactin synthetase Tomoko Abe1,2,3,4, Yoshiteru Hashimoto1,3, Sayaka Sugimoto1,3, Kenta Kobayashi2, Takuto Kumano1 and Michihiko Kobayashi1 The adenylation domain of nonribosomal peptide synthetase (NRPS) is responsible for the selective substrate recognition and its activation (as an acyl-O-AMP intermediate) during ATP consumption. DhbE, a stand-alone adenylation domain, acts on an aromatic acid, 2,3-dihydroxybenzoic acid (DHB). This activation is the initial step of the synthesis of bacillibactin that is a high-affinity small-molecule iron chelator also termed siderophore. Subsequently, the activated DHB is transferred and attached covalently to a peptidyl carrier protein domain via a thioester bond. Adenylation domains belong to the superfamily of adenylate-forming enzymes including acetyl-CoA synthetase, acyl-CoA synthetase and firefly luciferase. We previously reported a novel N-acylation reaction for an acyl-CoA synthetase (AcsA) that originally catalyzes the formation of a thioester bond between an acid and CoA, yielding acyl-CoA. This novel reaction was also confirmed for acetyl-CoA synthetase and firefly luciferase, but not yet for an adenylation domain. Here, we for the first time demonstrated the synthesis of N-acyl-L-cysteine by a stand-alone adenylation domain, DhbE. When DHB and L-cysteine were used as substrates of DhbE, N-DHB-L-cysteine was formed. A Vmax − 1 value of 0.0156 ± 0.0008 units mg and Km values of 150 ± 18.3 mM for L-cysteine and 0.0579 ± 0.0260 mM for DHB were obtained in this novel reaction.
    [Show full text]
  • Siderophore-Mediated Iron Acquisition in Bacillus Anthracis and Related Strains
    Microbiology (2010), 156, 1918–1925 DOI 10.1099/mic.0.039404-0 Mini-Review Siderophore-mediated iron acquisition in Bacillus anthracis and related strains Kinya Hotta,1 Chu-Young Kim,1 David T. Fox2 and Andrew T. Koppisch2 Correspondence 1Department of Biological Sciences, National University of Singapore, Singapore David T. Fox 2Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA [email protected] Andrew T. Koppisch [email protected] Recent observations have shed light on some of the endogenous iron-acquisition mechanisms of members of the Bacillus cereus sensu lato group. In particular, pathogens in the B. cereus group use siderophores with both unique chemical structures and biological roles. This review will focus on recent discoveries in siderophore biosynthesis and biology in this group, which contains numerous human pathogens, most notably the causative agent of anthrax, Bacillus anthracis. Introduction Siderophores of the Bacillus cereus sensu lato group Iron is a requisite nutrient for the growth and proliferation of bacteria. Unlike higher organisms, which may obtain Members of the B. cereus sensu lato group are known to bioavailable iron from the diet, bacteria must acquire iron produce and utilize two siderophores, bacillibactin (Fig. 1a, from their environment. This presents a challenging pro- boxed structure) and petrobactin (Fig. 2a, boxed structure) + blem, as soluble Fe3 in aqueous oxic environments typi- (Koppisch et al., 2005; Wilson et al., 2006). Both are cally exists at attomolar (10218) concentrations (Harris, considered catechol-based siderophores, in that the metal 2002). Iron homeostasis in a mammalian host is also is bound in the holo-siderophore either partially (petro- tightly regulated; virtually no iron exists in serum that is bactin) or entirely (bacillibactin) by dihydroxybenzoate not bound to haem, iron-storage proteins (ferritin, (DHB) units.
    [Show full text]
  • The Biochemistry of Siderophore Biosynthesis
    THE BIOCHEMISTRY OF SIDEROPHORE BIOSYNTHESIS By ©2007 Kathleen M. Meneely B.S., University of Kansas, 1999 Submitted to the Department of Molecular Biosciences and the Faculty of the Graduate School of the University of Kansas In partial fulfillment of the requirements for the degree of Doctor of Philosophy _______________________ Chairperson – Audrey Lamb _______________________ Committee members: Kristi Neufeld _______________________ Bill Picking _______________________ Mark Richter _______________________ Emily Scott Date defended: 11/14/2007 The Dissertation Committee for Kathleen Meneely certifies that this is the approved version of the following dissertation: THE BIOCHEMISTRY OF SIDEROPHORE BIOSYNTHESIS Committee: ________________________ Chairperson – Audrey Lamb ________________________ Kristi Neufeld ________________________ Bill Picking ________________________ Mark Richter ________________________ Emily Scott Date approved: 12/3/2007 ii Abstract Pathogenic bacteria are becoming increasingly antibiotic resistant. For this reason, the development of novel antibiotics is extremely important. A potential new target for antimicrobial drugs is the production of siderophores. Pseudomonas aeruginosa produces two siderophores under iron-limiting conditions, pyoverdin and pyochelin. Pyoverdin contains ornithine derivatives as part of the peptide backbone important for iron chelation. PvdA, an ornithine hydroxylase, performs the first step in derivation of the ornithine followed with formylation by PvdF, a formyl transferase. Biochemical characterization of PvdA reveals that PvdA is specific for the coenzymes, FAD and NADPH, as well as for the substrate, L-ornithine. The enzyme follows Michaelis-Menten kinetics measuring NADPH oxidation, but substrate inhibition is detected when measuring the formation of hydroxylated product. Lysine is determined as a nonsubstrate effector and mixed inhibitor of PvdA with respect to ornithine. Chloride is a competitive inhibitor of the enzyme in relation to NADPH while a mixed inhibitor with respect to substrate.
    [Show full text]
  • Heterogeneity in Respiratory Electron Transfer and Adaptive Iron Utilization in a Bacterial Biofilm
    ARTICLE https://doi.org/10.1038/s41467-019-11681-0 OPEN Heterogeneity in respiratory electron transfer and adaptive iron utilization in a bacterial biofilm Yuxuan Qin 1,2, Yinghao He 2, Qianxuan She 2, Philip Larese-Casanova3, Pinglan Li1 & Yunrong Chai2 In Bacillus subtilis, robust biofilm formation requires large quantities of ferric iron. Here we show that this process requires preferential production of a siderophore precursor, 2,3- dihydroxybenzoate, instead of the siderophore bacillibactin. A large proportion of iron is fi fi 1234567890():,; associated extracellularly with the bio lm matrix. The bio lms are conductive, with extra- cellular iron potentially acting as electron acceptor. A relatively small proportion of ferric iron is internalized and boosts production of iron-containing enzymes involved in respiratory electron transfer and establishing strong membrane potential, which is key to biofilm matrix production. Our study highlights metabolic diversity and versatile energy generation strate- gies within B. subtilis biofilms. 1 Beijing Advanced Innovation Center for Food Nutrition and Human Health, Key Laboratory of Functional Dairy, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. 2 Department of Biology, Northeastern University, Boston, MA 02115, USA. 3 Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA. Correspondence and requests for materials should be addressed to P.L. (email: [email protected]) or to Y.C. (email: [email protected]) NATURE COMMUNICATIONS | (2019) 10:3702 | https://doi.org/10.1038/s41467-019-11681-0 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-019-11681-0 ost bacteria are capable of forming surface-associated, and Δpps, Fig.
    [Show full text]
  • Structure Elucidation and Biosynthesis of Fuscachelins, Peptide Siderophores from the Moderate Thermophile Thermobifida Fusca
    Structure elucidation and biosynthesis of fuscachelins, peptide siderophores from the moderate thermophile Thermobifida fusca Eric J. Dimise, Paul F. Widboom, and Steven D. Bruner* Department of Chemistry, Boston College, Eugene F. Merkert Chemistry Center, Chestnut Hill, MA 02467 Edited by Christopher T. Walsh, Harvard Medical School, Boston, MA, and approved August 20, 2008 (received for review June 4, 2008) Bacteria belonging to the order Actinomycetales have proven to be an biosynthetic genes with the product, prediction of the peptide important source of biologically active and often therapeutically structure is possible. Despite several recent examples of this ap- useful natural products. The characterization of orphan biosynthetic proach, there remain aspects of NRP biosynthesis that are difficult gene clusters is an emerging and valuable approach to the discovery to predict, including uncommon amino acid incorporation, domain of novel small molecules. Analysis of the recently sequenced genome skipping/repeating, and macrocyclization. of the thermophilic actinomycete Thermobifida fusca revealed an Thermobifida fusca is a moderately thermophilic actinomycete orphan nonribosomal peptide biosynthetic gene cluster coding for an widely studied as a model organism for thermostable extracellular unknown siderophore natural product. T. fusca is a model organism cellulases (16–20). The genomic sequence of T. fusca YX was for the study of thermostable cellulases and is a major degrader of reported recently (21). There are no characterized secondary plant cell walls. Here, we report the isolation and structure elucidation metabolites from this actinomycete and few characterized natural of the fuscachelins, siderophore natural products produced by T. products from any thermophilic bacteria or archaea (22). One fusca.
    [Show full text]