Corrections CELL BIOLOGY MEDICAL SCIENCES Correction for “Dysregulation of PAD4-mediated citrullination Correction for “BRCA1 promotes the ubiquitination of PCNA of nuclear GSK3β activates TGF-β signaling and induces epithelial- and recruitment of translesion polymerases in response to rep- to-mesenchymal transition in breast cancer cells,” by Sonja C. lication blockade,” by Fen Tian, Shilpy Sharma, Jianqiu Zou, Stadler, C. Theresa Vincent, Victor D. Fedorov, Antonia Patsialou, Shiaw-Yih Lin, Bin Wang, Khosrow Rezvani, Hongmin Wang, Brian D. Cherrington, Joseph J. Wakshlag, Sunish Mohanan, Barry Jeffrey D. Parvin, Thomas Ludwig, Christine E. Canman, and M. Zee, Xuesen Zhang, Benjamin A. Garcia, John S. Condeelis, Dong Zhang, which appeared in issue 33, August 13, 2013, of Anthony M. C. Brown, Scott A. Coonrod, and C. David Allis, which Proc Natl Acad Sci USA (110:13558–13563; first published July appeared in issue 29, July 16, 2013, of Proc Natl Acad Sci USA 30, 2013; 10.1073/pnas.1306534110). (110:11851–11856; first published July 1, 2013; 10.1073/pnas. The authors note that they omitted a reference to an article by 1308362110). Pathania et al. The complete reference appears below. The authors note that the affiliation for C. Theresa Vincent Furthermore, the authors note that “It is important to note should also include kCell and Developmental Biology, Weill that the role of BRCA1 in response to UV induced replication Cornell Medical College, New York, NY 10065. The corrected stress has also been examined by Livingston and colleagues (41). author and affiliation lines appear below. The online version has Both studies observed some overlapping phenotypes in BRCA1 been corrected. depleted cells (for example, the reduction of RPA foci when treated with UV). However, the two studies also have some discrep- Sonja C. Stadlera,b, C. Theresa Vincentc,d,k, Victor D. ancies with respect to PCNA ubiquitination. We speculate that Fedorove, Antonia Patsialouf, Brian D. Cherringtong, these discrepancies may be due to the knockdown efficiency BRCA1 ” Joseph J. Wakshlagh, Sunish Mohanani, Barry M. Zeej, of . Xuesen Zhangi, Benjamin A. Garciaj, John S. Condeelisf, k i Anthony M. C. Brown , Scott A. Coonrod , 41. Pathania S, et al. (2011) BRCA1 is required for postreplication repair after UV-induced and C. David Allisa DNA damage. Mol Cell 44(2):235–251. www.pnas.org/cgi/doi/10.1073/pnas.1316463110 aLaboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065; bInstitute of Laboratory Medicine, Clinical Chemistry, and Molecular Diagnostics and LIFE Leipzig Research Center for Civilization Diseases, University of Leipzig, 04103 Leipzig, Germany; Departments of cPhysiology and Biophysics and kCell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065; dDepartment of Medicine, Center for Molecular Medicine, Karolinska Institutet, 171 76 PLANT BIOLOGY Stockholm, Sweden; eCenter for Cell Engineering, Molecular Pharmacology Correction for “Dirigent domain-containing protein is part of the and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New f machinery required for formation of the lignin-based Casparian York, NY 10065; Department of Anatomy and Structural Biology, Albert ” Einstein College of Medicine, Bronx, NY 10461; gDepartment of Zoology strip in the root, by Prashant S. Hosmani, Takehiro Kamiya, and Physiology, University of Wyoming, Laramie, WY 82071; hDepartment John Danku, Sadaf Naseer, Niko Geldner, Mary Lou Guerinot, of Clinical Sciences and iBaker Institute for Animal Health, College of and David E. Salt, which appeared in issue 35, August 27, 2013, j Veterinary Medicine, Cornell University, Ithaca, NY 14853; and Department of Proc Natl Acad Sci USA (110:14498–14503; first published of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 August 12, 2013; 10.1073/pnas.1308412110). The authors note that the contributions line appeared incor- www.pnas.org/cgi/doi/10.1073/pnas.1315590110 rectly. The corrected author contributions footnote appears below. P.S.H., T.K., N.G., M.L.G., and D.E.S. designed research; P.S.H., T.K., J.D., and S.N. performed research; P.S.H., T.K., J.D., S.N., N.G., M.L.G., and D.E.S. analyzed data; and P.S.H. and D.E.S. wrote the paper. www.pnas.org/cgi/doi/10.1073/pnas.1315919110 CORRECTIONS www.pnas.org PNAS | October 1, 2013 | vol. 110 | no. 40 | 16283 Downloaded by guest on September 23, 2021 Dirigent domain-containing protein is part of the machinery required for formation of the lignin-based Casparian strip in the root Prashant S. Hosmania, Takehiro Kamiyab, John Dankub, Sadaf Naseerc, Niko Geldnerc, Mary Lou Guerinota, and David E. Saltb,1 aDepartment of Biological Sciences, Dartmouth College, Hanover, NH 03755; bInstitute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU, United Kingdom; and cDepartment of Plant Molecular Biology, University of Lausanne–Sorge, 1015 Lausanne, Switzerland Edited by Philip N. Benfey, Duke University, Durham, NC, and approved July 22, 2013 (received for review May 7, 2013) The endodermis acts as a “second skin” in plant roots by providing Results and Discussion the cellular control necessary for the selective entry of water and Enhanced suberin1 (ESB1) was originally identified in a forward solutes into the vascular system. To enable such control, Casparian genetic screen of Arabidopsis thaliana for mutants with altered strips span the cell wall of adjacent endodermal cells to form mineral nutrient and trace element contents (8, 9). The esb1 a tight junction that blocks extracellular diffusion across the en- mutant displays changes in the leaf accumulation of various dodermis. This junction is composed of lignin that is polymerized elements, including a significant reduction in calcium, which are by oxidative coupling of monolignols through the action of a proposed to be caused by the observed increase of suberin de- NADPH oxidase and peroxidases. Casparian strip domain proteins position in the roots of this mutant (8, 10). ESB1 encodes a (CASPs) correctly position this biosynthetic machinery by forming protein containing a predicted 154-aa residue dirigent domain a protein scaffold in the plasma membrane at the site where the (Pfam 26.0 PF03018) (11). Dirigent proteins have been charac- Casparian strip forms. Here, we show that the dirigent-domain terized to act as nonenzymatic templates guiding bond formation containing protein, enhanced suberin1 (ESB1), is part of this machin- between two monolignols to define the stereochemistry of the ery, playing an essential role in the correct formation of Casparian resulting dimeric lignin (12). It has been suggested that dirigent strips. ESB1 is localized to Casparian strips in a CASP-dependent proteins can guide synthesis of lignin by providing a template for manner, and in the absence of ESB1, disordered and defective Cas- a specific order of monolignol subunits during lignin deposition parian strips are formed. In addition, loss of ESB1 disrupts the lo- in the cell wall (13), but these observations need to be reconciled calization of the CASP1 protein at the casparian strip domain, with biochemical evidence that lignin polymerization can occur suggesting a reciprocal requirement for both ESB1 and CASPs in in the absence of proteinaceous control (14). Here, we demon- forming the casparian strip domain strate that the dirigent domain containing protein ESB1 is re- quired for the correct patterning of lignin deposition in he root is the central plant organ required for water and Casparian strips. Use of a stably expressed protein fusion of Tmineral nutrient uptake from the soil. Understanding the ESB1 with red fluorescent mCherry under the transcriptional mechanisms underlying root function is therefore central for control of the ESB1 native promoter revealed that ESB1 is developing plants with the improved root systems required for uniquely expressed in the endodermis (Fig. 1 A–C) and localizes the more efficient water and mineral nutrient utilization needed in a band-like structure around the endodermal cells in a similar to drive sustainable increases in food production and quality. pattern to Casparian strips (Fig. 1 D and E). Interestingly, ESB1- The rate limiting step in water and mineral nutrient transport to mCherry appears to initially localize along the equatorial line of the shoot is radial transport across the root (1). Radial transport the endodermal cell in patches, which then coalesce to form involves movement of water and dissolved solutes from the soil, through the epidermis, cortex, and endodermal cell layers and Significance into the vascular system (1). Transport occurs through the cell wall continuum (apoplasm) or cell to cell by using symplastic or The endodermis acts as a “second skin” in plant roots by transmembrane pathways. The differentiation of the endodermis providing the cellular control necessary for the selective entry is marked by the formation in the cell wall of the Casparian strip, of water and mineral nutrients into the vascular system. To a belt-like structure surrounding the cell and running parallel to enable such control, Casparian strips span the cell wall of the root surface in the anticlinal cell wall. This structure is adjacent endodermal cells to form a tight junction that blocks fi composed of a ne band of lignin (2) tightly adhered to the diffusion across the endodermis in the cell wall. This junction plasma membrane and spanning the apoplastic space between is composed of a fine band of lignin, the polymer that gives adjacent endodermal cells. Casparian strips form a physical wood its strength. Here, we characterize a dirigent protein barrier to extracellular diffusion (3, 4), allowing endodermal cells (from Latin, dirigere: to guide or align) as playing a vital role to exert control over passage of water and solutes into the stele in the patterning of lignin in the Casparian strip, identifying and the vascular system for transport throughout the plant (5). a new component of the molecular machinery that builds Lignin-forming Casparian strips is polymerized by oxidative Casparian strips.