1
|
Guo C, Feng Z, Zuo G, Jiang YL, Zhou CZ, Chen Y, Hou WT. Structural and functional insights into the Asp1/2/3 complex mediated secretion of pneumococcal serine-rich repeat protein PsrP. Biochem Biophys Res Commun 2020; 524:784-790. [PMID: 32037091 DOI: 10.1016/j.bbrc.2020.01.146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 01/27/2020] [Indexed: 11/29/2022]
Abstract
The accessory sec system consisting of seven conserved components is commonly distributed among pathogenic Gram-positive bacteria for the secretion of serine-rich-repeat proteins (SRRPs). Asp1/2/3 protein complex in the system is responsible for both the O-acetylation of GlcNAc and delivering SRRPs to SecA2. However, the molecular mechanism of how Asp1/2/3 transport SRRPs remains unknown. Here, we report the complex structure of Asp1/2/3 from Streptococcus pneumoniae at 2.9 Å. Further functional assays indicated that Asp1/2/3 can stimulate the ATPase activity of SecA2. In addition, the deletion of asp1/2/3 gene resulted in the accumulation of a secreted version of PsrP with an altered glycoform in protoplast fraction of the mutant cell, which suggested the modification/transport coupling of the substrate. Altogether, these findings not only provide structural basis for further investigations on the transport process of SRRPs, but also uncover the indispensable role of Asp1/2/3 in the accessory sec system.
Collapse
Affiliation(s)
- Cong Guo
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Zhang Feng
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Gang Zuo
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yong-Liang Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Cong-Zhao Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yuxing Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China.
| | - Wen-Tao Hou
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, China.
| |
Collapse
|
2
|
Chen Y, Bensing BA, Seepersaud R, Mi W, Liao M, Jeffrey PD, Shajahan A, Sonon RN, Azadi P, Sullam PM, Rapoport TA. Unraveling the sequence of cytosolic reactions in the export of GspB adhesin from Streptococcus gordonii. J Biol Chem 2018; 293:5360-5373. [PMID: 29462788 DOI: 10.1074/jbc.ra117.000963] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/05/2018] [Indexed: 12/24/2022] Open
Abstract
Many pathogenic bacteria, including Streptococcus gordonii, possess a pathway for the cellular export of a single serine-rich-repeat protein that mediates the adhesion of bacteria to host cells and the extracellular matrix. This adhesin protein is O-glycosylated by several cytosolic glycosyltransferases and requires three accessory Sec proteins (Asp1-3) for export, but how the adhesin protein is processed for export is not well understood. Here, we report that the S. gordonii adhesin GspB is sequentially O-glycosylated by three enzymes (GtfA/B, Nss, and Gly) that attach N-acetylglucosamine and glucose to Ser/Thr residues. We also found that modified GspB is transferred from the last glycosyltransferase to the Asp1/2/3 complex. Crystal structures revealed that both Asp1 and Asp3 are related to carbohydrate-binding proteins, suggesting that they interact with carbohydrates and bind glycosylated adhesin, a notion that was supported by further analyses. We further observed that Asp1 also has an affinity for phospholipids, which is attenuated by Asp2. In summary, our findings support a model in which the GspB adhesin is sequentially glycosylated by GtfA/B, Nss, and Gly and then transferred to the Asp1/2/3 complex in which Asp1 mediates the interaction of the Asp1/2/3 complex with the lipid bilayer for targeting of matured GspB to the export machinery.
Collapse
Affiliation(s)
- Yu Chen
- From the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Barbara A Bensing
- the Department of Medicine, San Francisco Veteran Affairs Medical Center, University of California at San Francisco, San Francisco, California 94121
| | - Ravin Seepersaud
- the Department of Medicine, San Francisco Veteran Affairs Medical Center, University of California at San Francisco, San Francisco, California 94121
| | - Wei Mi
- From the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Maofu Liao
- From the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Philip D Jeffrey
- the Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544
| | - Asif Shajahan
- the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Roberto N Sonon
- the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Parastoo Azadi
- the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, and
| | - Paul M Sullam
- the Department of Medicine, San Francisco Veteran Affairs Medical Center, University of California at San Francisco, San Francisco, California 94121
| | - Tom A Rapoport
- From the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, .,the Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
3
|
Zhu F, Zhang H, Yang T, Haslam SM, Dell A, Wu H. Engineering and Dissecting the Glycosylation Pathway of a Streptococcal Serine-rich Repeat Adhesin. J Biol Chem 2017; 291:27354-27363. [PMID: 28039332 PMCID: PMC5207161 DOI: 10.1074/jbc.m116.752998] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 11/11/2016] [Indexed: 11/24/2022] Open
Abstract
Serine-rich repeat glycoproteins (SRRPs) are conserved in Gram-positive bacteria. They are crucial for modulating biofilm formation and bacterial-host interactions. Glycosylation of SRRPs plays a pivotal role in the process; thus understanding the glycosyltransferases involved is key to identifying new therapeutic drug targets. The glycosylation of Fap1, an SRRP of Streptococcus parasanguinis, is mediated by a gene cluster consisting of six genes: gtf1, gtf2, gly, gtf3, dGT1, and galT2. Mature Fap1 glycan possesses the sequence of Rha1–3Glc1-(Glc1–3GlcNAc1)-2,6-Glc1–6GlcNAc. Gtf12, Gtf3, and dGT1 are responsible for the first four steps of the Fap1 glycosylation, catalyzing the transfer of GlcNAc, Glc, Glc, and GlcNAc residues to the protein backbone sequentially. The role of GalT2 and Gly in the Fap1 glycosylation is unknown. In the present study, we synthesized the fully modified Fap1 glycan in Escherichia coli by incorporating all six genes from the cluster. This study represents the first reconstitution of an exogenous stepwise O-glycosylation synthetic pathway in E. coli. In addition, we have determined that GalT2 mediates the fifth step of the Fap1 glycosylation by adding a rhamnose residue, and Gly mediates the final glycosylation step by transferring glucosyl residues. Furthermore, inactivation of each glycosyltransferase gene resulted in differentially impaired biofilms of S. parasanguinis, demonstrating the importance of Fap1 glycosylation in the biofilm formation. The Fap1 glycosylation system offers an excellent model to engineer glycans using different permutations of glycosyltransferases and to investigate biosynthetic pathways of SRRPs because SRRP genetic loci are highly conserved.
Collapse
Affiliation(s)
- Fan Zhu
- From the Departments of Pediatric Dentistry and.,Microbiology, University of Alabama at Birmingham, Schools of Dentistry and Medicine, Birmingham, Alabama 35244 and
| | - Hua Zhang
- From the Departments of Pediatric Dentistry and
| | - Tiandi Yang
- the Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Stuart M Haslam
- the Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Anne Dell
- the Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hui Wu
- From the Departments of Pediatric Dentistry and .,Microbiology, University of Alabama at Birmingham, Schools of Dentistry and Medicine, Birmingham, Alabama 35244 and
| |
Collapse
|
4
|
Zhang H, Zhou M, Yang T, Haslam SM, Dell A, Wu H. New Helical Binding Domain Mediates a Glycosyltransferase Activity of a Bifunctional Protein. J Biol Chem 2016; 291:22106-22117. [PMID: 27539847 PMCID: PMC5063993 DOI: 10.1074/jbc.m116.731695] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 11/08/2022] Open
Abstract
Serine-rich repeat glycoproteins (SRRPs) conserved in streptococci and staphylococci are important for bacterial colonization and pathogenesis. Fap1, a well studied SRRP is a major surface constituent of Streptococcus parasanguinis and is required for bacterial adhesion and biofilm formation. Biogenesis of Fap1 is a multistep process that involves both glycosylation and secretion. A series of glycosyltransferases catalyze sequential glycosylation of Fap1. We have identified a unique hybrid protein dGT1 (dual glycosyltransferase 1) that contains two distinct domains. N-terminal DUF1792 is a novel GT-D-type glycosyltransferase, transferring Glc residues to Glc-GlcNAc-modified Fap1. C-terminal dGT1 (CgT) is predicted to possess a typical GT-A-type glycosyltransferase, however, the activity remains unknown. In this study, we determine that CgT is a distinct glycosyltransferase, transferring GlcNAc residues to Glc-Glc-GlcNAc-modified Fap1. A 2.4-Å x-ray crystal structure reveals that CgT has a unique binding domain consisting of three α helices in addition to a typical GT-A-type glycosyltransferase domain. The helical domain is crucial for the oligomerization of CgT. Structural and biochemical studies revealed that the helix domain is required for the protein-protein interaction and crucial for the glycosyltransferase activity of CgT in vitro and in vivo. As the helix domain presents a novel structural fold, we conclude that CgT represents a new member of GT-A-type glycosyltransferases.
Collapse
Affiliation(s)
- Hua Zhang
- From the Departments of Pediatric Dentistry and Microbiology, Schools of Dentistry and Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Meixian Zhou
- From the Departments of Pediatric Dentistry and Microbiology, Schools of Dentistry and Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| | - Tiandi Yang
- the Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Stuart M Haslam
- the Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Anne Dell
- the Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Hui Wu
- From the Departments of Pediatric Dentistry and Microbiology, Schools of Dentistry and Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294 and
| |
Collapse
|
5
|
A conserved domain is crucial for acceptor substrate binding in a family of glucosyltransferases. J Bacteriol 2014; 197:510-7. [PMID: 25404702 DOI: 10.1128/jb.02267-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serine-rich repeat glycoproteins (SRRPs) are highly conserved in streptococci and staphylococci. Glycosylation of SRRPs is important for bacterial adhesion and pathogenesis. Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis among newborns. Srr2, an SRRP from S. agalactiae strain COH1, has been implicated in bacterial virulence. Four genes (gtfA, gtfB, gtfC, and gtfD) located downstream of srr2 share significant homology with genes involved in glycosylation of other SRRPs. We have shown previously that gtfA and gtfB encode two glycosyltransferases, GtfA and GtfB, that catalyze the transfer of GlcNAc residues to the Srr2 polypeptide. However, the function of other glycosyltransferases in glycosylation of Srr2 is unknown. In this study, we determined that GtfC catalyzed the direct transfer of glucosyl residues to Srr2-GlcNAc. The GtfC crystal structure was solved at 2.7 Å by molecular replacement. Structural analysis revealed a loop region at the N terminus as a putative acceptor substrate binding domain. Deletion of this domain rendered GtfC unable to bind to its substrate Srr2-GlcNAc, concurrently abolished the glycosyltransferase activity of GtfC, and also altered glycosylation of Srr2. Furthermore, deletion of the corresponding regions from GtfC homologs also abolished their substrate binding and enzymatic activity, indicating that this region is functionally conserved. In summary, we have determined that GtfC is important for the glycosylation of Srr2 and identified a conserved loop region that is crucial for acceptor substrate binding from GtfC homologs in streptococci. These findings shed new mechanistic insight into this family of glycosyltransferases.
Collapse
|
6
|
Bensing BA, Seepersaud R, Yen YT, Sullam PM. Selective transport by SecA2: an expanding family of customized motor proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:1674-86. [PMID: 24184206 DOI: 10.1016/j.bbamcr.2013.10.019] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 10/20/2013] [Accepted: 10/23/2013] [Indexed: 01/22/2023]
Abstract
The SecA2 proteins are a special class of transport-associated ATPases that are related to the SecA component of the general Sec system, and are found in an increasingly large number of Gram-positive bacterial species. The SecA2 substrates are typically linked to the cell wall, but may be lipid-linked, peptidoglycan-linked, or non-covalently associated S-layer proteins. These substrates can have a significant impact on virulence of pathogenic organisms, but may also aid colonization by commensals. The SecA2 orthologues range from being highly similar to their SecA paralogues, to being distinctly different in apparent structure and function. Two broad classes of SecA2 are evident. One transports multiple substrates, and may interact with the general Sec system, or with an as yet unidentified transmembrane channel. The second type transports a single substrate, and is a component of the accessory Sec system, which includes the SecY paralogue SecY2 along with the accessory Sec proteins Asp1-3. Recent studies indicate that the latter three proteins may have a unique role in coordinating post-translational modification of the substrate with transport by SecA2. Comparative functional and phylogenetic analyses suggest that each SecA2 may be uniquely adapted for a specific type of substrate. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
Collapse
Affiliation(s)
- Barbara A Bensing
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA.
| | - Ravin Seepersaud
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
| | - Yihfen T Yen
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
| | - Paul M Sullam
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
| |
Collapse
|
7
|
Iwashkiw JA, Vozza NF, Kinsella RL, Feldman MF. Pour some sugar on it: the expanding world of bacterial proteinO-linked glycosylation. Mol Microbiol 2013; 89:14-28. [DOI: 10.1111/mmi.12265] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2013] [Indexed: 11/26/2022]
Affiliation(s)
- Jeremy A. Iwashkiw
- Alberta Glycomics Centre; Department of Biological Sciences; University of Alberta; CW405 Biological Sciences Building; Edmonton; Alberta; Canada; T6G 2E9
| | - Nicolas F. Vozza
- Alberta Glycomics Centre; Department of Biological Sciences; University of Alberta; CW405 Biological Sciences Building; Edmonton; Alberta; Canada; T6G 2E9
| | - Rachel L. Kinsella
- Alberta Glycomics Centre; Department of Biological Sciences; University of Alberta; CW405 Biological Sciences Building; Edmonton; Alberta; Canada; T6G 2E9
| | - Mario F. Feldman
- Alberta Glycomics Centre; Department of Biological Sciences; University of Alberta; CW405 Biological Sciences Building; Edmonton; Alberta; Canada; T6G 2E9
| |
Collapse
|