With Antibacterial Peptides Gram-Negative Bacteria and Are
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Human Peptidoglycan Recognition Proteins Require Zinc to Kill Both Gram-Positive and Gram-Negative Bacteria and Are Synergistic with Antibacterial Peptides This information is current as of September 29, 2021. Minhui Wang, Li-Hui Liu, Shiyong Wang, Xinna Li, Xiaofeng Lu, Dipika Gupta and Roman Dziarski J Immunol 2007; 178:3116-3125; ; doi: 10.4049/jimmunol.178.5.3116 http://www.jimmunol.org/content/178/5/3116 Downloaded from References This article cites 63 articles, 33 of which you can access for free at: http://www.jimmunol.org/content/178/5/3116.full#ref-list-1 http://www.jimmunol.org/ Why The JI? Submit online. • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication by guest on September 29, 2021 *average Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2007 by The American Association of Immunologists All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. The Journal of Immunology Human Peptidoglycan Recognition Proteins Require Zinc to Kill Both Gram-Positive and Gram-Negative Bacteria and Are Synergistic with Antibacterial Peptides1 Minhui Wang, Li-Hui Liu, Shiyong Wang, Xinna Li, Xiaofeng Lu, Dipika Gupta, and Roman Dziarski2 Mammals have four peptidoglycan recognition proteins (PGRPs or PGLYRPs), which are secreted innate immunity pattern recognition molecules with effector functions. In this study, we demonstrate that human PGLYRP-1, PGLYRP-3, PGLYRP-4, and PGLYRP-3:4 have Zn2؉-dependent bactericidal activity against both Gram-positive and Gram-negative bacteria at physiologic Zn2؉ concentrations found in serum, sweat, saliva, and other body fluids. The requirement for Zn2؉ can only be partially replaced 2؉ by Ca for killing of Gram-positive bacteria but not for killing of Gram-negative bacteria. The bactericidal activity of PGLYRPs Downloaded from is salt insensitive and requires N-glycosylation of PGLYRPs. The LD99 of PGLYRPs for Gram-positive and Gram-negative bacteria is 0.3–1.7 M, and killing of bacteria by PGLYRPs, in contrast to killing by antibacterial peptides, does not involve ␣  permeabilization of cytoplasmic membrane. PGLYRPs and antibacterial peptides (phospholipase A2, - and -defensins, and bactericidal permeability-increasing protein), at subbactericidal concentrations, synergistically kill Gram-positive and Gram- negative bacteria. These results demonstrate that PGLYRPs are a novel class of recognition and effector molecules with broad 2؉ Zn -dependent bactericidal activity against both Gram-positive and Gram-negative bacteria that are synergistic with antibac- http://www.jimmunol.org/ terial peptides. The Journal of Immunology, 2007, 178: 3116–3125. eptidoglycan recognition proteins (PGRPs)3 are innate im- zation Gene Nomenclature Committee changed their names to munity molecules present in insects, mollusks, echino- peptidoglycan recognition proteins 1, 2, 3, and 4 (PGLYRP-1, P derms, and vertebrates but not in nematodes and plants PGLYRP-2, PGLYRP-3, and PGLYRP-4), respectively, and (1–3). PGRPs have at least one PGRP domain, which is homolo- this terminology is used here. gous to bacteriophage and bacterial type 2 amidases (1–3). Insects Mammalian PGLYRP-2 is an N-acetylmuramoyl-L-alanine ami- have up to 19 PGRPs, classified into short (S) and long (L) forms dase that hydrolyzes bacterial peptidoglycan (5, 6). PGLYRP-2 is by guest on September 29, 2021 (3). The short forms are present in the hemolymph, cuticle, and fat secreted from liver into blood and is also induced by bacteria in body cells and sometimes in epidermal cells in the gut and hemo- epithelial cells (7–9). The remaining three mammalian PGLYRPs cytes, whereas the long forms are mainly expressed in hemocytes are bactericidal or bacteriostatic proteins that are secreted as (3). The expression of insect PGRPs is often up-regulated by ex- disulfide-linked homo- and heterodimers (10). Mammalian posure to bacteria. Insect PGRPs activate Toll or Imd signal trans- PGLYRP-1, PGLYRP-3, and PGLYRP-4 are a new class of bac- duction pathways or induce proteolytic cascades that generate an- tericidal proteins that have a different structure, mechanism of ac- timicrobial products, induce phagocytosis, and protect insects tion, and expression than currently known mammalian antimicro- against infections (3). Some insect PGRPs are enzymes that hy- bial peptides (10, 11). PGLYRPs are much larger than all currently drolyze peptidoglycan, a bacterial cell wall component (3). known vertebrate antibacterial peptides: they are disulfide-linked Mammals have four PGRPs, which were initially named glycosylated 44- to 115-kDa dimers, in contrast to vertebrate PGRP-S, PGRP-L, and PGRP-I␣ and PGRP-I (for “short”, antimicrobial peptides, which are typically 3–15 kDa (10, 11). “long”, or “intermediate” transcripts, respectively), by analogy to PGLYRPs kill bacteria likely by interacting with cell wall pepti- insect PGRPs (3, 4). Subsequently, the Human Genome Organi- doglycan, whereas antibacterial peptides kill bacteria by perme- abilizing their membranes (10). PGLYRPs require divalent cations Indiana University School of Medicine, Northwest Campus, Gary, IN 46408 and N-glycosylation for their bactericidal activity, and antibacterial Received for publication October 11, 2006. Accepted for publication December 14, peptides usually do not (10, 11). 2006. PGLYRP-1 is expressed primarily in PMN granules (12–15), The costs of publication of this article were defrayed in part by the payment of page and PGLYRP-3 and PGLYRP-4 are expressed in the skin, eyes, charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. salivary glands, throat, tongue, esophagus, stomach, and intestine 1 This work was supported by U.S. Public Health Service Grants AI28797 and (10). In addition to PGLYRPs, these tissues also express many AI56395 from the National Institutes of Health. antimicrobial peptides and proteins, such as defensins (16, 17), 2 Address correspondence and reprint requests to Dr. Roman Dziarski, Indiana Uni- phospholipase A2 (18–22), dermicidin (23), cathelicidin (24), versity School of Medicine, Northwest Campus, 3400 Broadway, Gary, IN 46408. E-mail address: [email protected] RNases (25), psoriasin (26), calprotectin (27–29), bactericidal per- meability-increasing protein (22), and lysozyme (22). Secretions of 3 Abbreviations used in this paper: PGRP or PGLYRP, peptidoglycan recognition pro- 2ϩ teins; BPI, bactericidal permeability-increasing protein; HBD-3, human -defensin-3; these tissues also contain several divalent cations, such as Ca , HNP-1, human neutrophil protein-1 (␣-defensin); LTA, lipoteichoic acid; MurNAc, Mg2ϩ,Zn2ϩ,Fe2ϩ,Cu2ϩ,Se2ϩ,Ni2ϩ, and Mn2ϩ (30), which influ- N-acetylmuramic acid; LB, Luria-Bertani; PLA , group IIA phospholipase A . 2 2 ence the activity of antimicrobial proteins. Because our previous Copyright © 2007 by The American Association of Immunologists, Inc. 0022-1767/07/$2.00 results indicated that bactericidal activity of human PGLYRPs for www.jimmunol.org The Journal of Immunology 3117 ϩ Gram-positive bacteria is Ca2 dependent (10) and because other Table I. Concentrations of divalent cations in human sweat and saliva divalent cations present in body secretions and tissue fluids influ- and in PGLYRP bactericidal assay buffer ence the activity of other antimicrobial proteins (16, 17, 27–40), in this study, we tested the hypothesis that other divalent cations may Cation Sweat Saliva Assay Buffersa also play an important role in bactericidal activity of human Ca2ϩ 0.5 mM 2 mM 1 mM PGLYRPs. Moreover, because PGLYRPs are secreted into body Mg2ϩ 100 M40M50M fluids that also contain many antibacterial peptides with different Zn2ϩ 17 M2M5M 2ϩ bactericidal mechanisms from PGLYRPs (10), we also tested the Fe 6 M6M5M Cu2ϩ 5 M5M5M hypothesis that PGLYRPs may kill bacteria synergistically with ϩ Se2 1 M39nM these peptides. We discovered that PGLYRPs have higher bacte- Ni2ϩ 0.8 M0 ricidal activity against Gram-positive bacteria and become highly Mn2ϩ 0.4 M0 1M 2ϩ bactericidal for Gram-negative bacteria in the presence Zn and a Final concentration of ions in the bactericidal assays used individually or in also that PGLYRPs kill bacteria synergistically together with combinations as indicated in Figs. 1 and 2. Two times higher concentrations were membrane-damaging antibacterial peptides. used for protein purification and storage buffers, and other components were used as described in Materials and Methods. Materials and Methods Materials concentrations indicated in Results. The standard medium was 5 mM Tris Human PGLYRP-1, PGLYRP-3, PGLYRP-4, and PGLYRP-3:4 were ex- (pH 7.6), with 150 mM NaCl, 5 M ZnSO4, 5% glycerol, and 1% Luria- pressed in S2 cells and purified as previously described (10), except that Bertani (LB) for Gram-negative bacteria, or the same medium plus 1 mM Downloaded from 2ϩ 2ϩ instead of Ca ,40MZn (for testing on Gram-negative bacteria) or 2 CaCl2 and 5 M CuSO4 and either 1% LB or 1% BHI for Gram-positive mM Ca2ϩ,40MZn2ϩ, and 10 MCu2ϩ (for testing on Gram-positive bacteria (10), unless otherwise indicated (i.e., in some experiments com- bacteria) were used in protein purification buffers, and 10 MZn2ϩ (for binations of various divalent cations listed in Table I were used, as indi- Gram-negative bacteria) or 2 mM Ca2ϩ,10MZn2ϩ, and 10 MCu2ϩ cated in Results). The numbers of bacteria were determined by colony (for Gram-positive bacteria) were used in the final dialysis buffer. Wher- counts on LB or BHI agar plates (10).