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Dahlgren KK, Gates C, Lee T, Cameron JC. Proximity-based proteomics reveals the thylakoid lumen proteome in the cyanobacterium Synechococcus sp. PCC 7002. PHOTOSYNTHESIS RESEARCH 2021; 147:177-195. [PMID: 33280076 PMCID: PMC7880944 DOI: 10.1007/s11120-020-00806-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
Cyanobacteria possess unique intracellular organization. Many proteomic studies have examined different features of cyanobacteria to learn about the intracellular structures and their respective functions. While these studies have made great progress in understanding cyanobacterial physiology, the conventional fractionation methods used to purify cellular structures have limitations; specifically, certain regions of cells cannot be purified with existing fractionation methods. Proximity-based proteomics techniques were developed to overcome the limitations of biochemical fractionation for proteomics. Proximity-based proteomics relies on spatiotemporal protein labeling followed by mass spectrometry of the labeled proteins to determine the proteome of the region of interest. We performed proximity-based proteomics in the cyanobacterium Synechococcus sp. PCC 7002 with the APEX2 enzyme, an engineered ascorbate peroxidase. We determined the proteome of the thylakoid lumen, a region of the cell that has remained challenging to study with existing methods, using a translational fusion between APEX2 and PsbU, a lumenal subunit of photosystem II. Our results demonstrate the power of APEX2 as a tool to study the cell biology of intracellular features and processes, including photosystem II assembly in cyanobacteria, with enhanced spatiotemporal resolution.
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Affiliation(s)
- Kelsey K Dahlgren
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309, USA
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO, 80309, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO, 80309, USA
- Interdisciplinary Quantitative Biology Program (IQ Biology), BioFrontiers Institute, University of Colorado, Boulder, CO, 80309, USA
| | - Colin Gates
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO, 80309, USA
| | - Thomas Lee
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309, USA
| | - Jeffrey C Cameron
- Department of Biochemistry, University of Colorado, Boulder, CO, 80309, USA.
- Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO, 80309, USA.
- National Renewable Energy Laboratory, Golden, CO, 80401, USA.
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Kang L, Li N, Li P, Zhou Y, Gao S, Gao H, Xin W, Wang J. MALDI-TOF mass spectrometry provides high accuracy in identification of Salmonella at species level but is limited to type or subtype Salmonella serovars. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2017; 23:70-82. [PMID: 28657416 DOI: 10.1177/1469066717699216] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Salmonella can cause global foodborne illnesses in humans and many animals. The current diagnostic gold standard used for detecting Salmonella infection is microbiological culture followed by serological confirmation tests. However, these methods are complicated and time-consuming. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis offers some advantages in rapid identification, for example, simple and fast sample preparation, fast and automated measurement, and robust and reliable identification up to genus and species levels, possibly even to the strain level. In this study, we established a reference database for species identification using whole-cell MALDI-TOF MS; the database consisted of 12 obtained main spectra of the Salmonella culture collection strains belonged to seven serotypes. Eighty-two clinical isolates of Salmonella were identified using established database, and partial 16S rDNA gene sequencing and serological method were used as comparison. We found that MALDI-TOF mass spectrometry provided high accuracy in identification of Salmonella at species level but was limited to type or subtype Salmonella serovars. We also tried to find serovar-specific biomarkers and failed. Our study demonstrated that (a) MALDI-TOF MS was suitable for identification of Salmonella at species level with high accuracy and (b) that MALDI-TOF MS method presented in this study was not useful for serovar assignment of Salmonella currently, because of its low matching with serological method and (c) MALDI-TOF MS method presented in this study was not suitable to subtype S. typhimurium because of its low discriminatory ability.
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Affiliation(s)
- Lin Kang
- 1 State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, People's Republic of China
| | - Nan Li
- 2 Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, People's Republic of China
| | - Ping Li
- 1 State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, People's Republic of China
- 3 Graduate College, Anhui Medical University, Anhui, People's Republic of China
| | - Yang Zhou
- 1 State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, People's Republic of China
| | - Shan Gao
- 1 State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, People's Republic of China
| | - Hongwei Gao
- 2 Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, People's Republic of China
| | - Wenwen Xin
- 1 State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, People's Republic of China
| | - Jinglin Wang
- 1 State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, People's Republic of China
- 3 Graduate College, Anhui Medical University, Anhui, People's Republic of China
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Gao L, Wang J, Ge H, Fang L, Zhang Y, Huang X, Wang Y. Toward the complete proteome of Synechocystis sp. PCC 6803. PHOTOSYNTHESIS RESEARCH 2015; 126:203-219. [PMID: 25862646 DOI: 10.1007/s11120-015-0140-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 04/02/2015] [Indexed: 06/04/2023]
Abstract
The proteome of the photosynthetic model organism Synechocystis sp. PCC 6803 has been extensively analyzed in the last 15 years for the purpose of identifying proteins specifically expressed in subcellular compartments or differentially expressed in different environmental or internal conditions. This review summarizes the progress achieved so far with the emphasis on the impact of different techniques, both in sample preparation and protein identification, on the increasing coverage of proteome identification. In addition, this review evaluates the current completeness of proteome identification, and provides insights on the potential factors that could affect the complete identification of the Synechocystis proteome.
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Affiliation(s)
- Liyan Gao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China
| | - Jinlong Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China
| | - Haitao Ge
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, China
| | - Longfa Fang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China
| | - Yuanya Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China
| | - Xiahe Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China.
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Plohnke N, Seidel T, Kahmann U, Rögner M, Schneider D, Rexroth S. The proteome and lipidome of Synechocystis sp. PCC 6803 cells grown under light-activated heterotrophic conditions. Mol Cell Proteomics 2015; 14:572-84. [PMID: 25561504 PMCID: PMC4349978 DOI: 10.1074/mcp.m114.042382] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/10/2014] [Indexed: 12/31/2022] Open
Abstract
Cyanobacteria are photoautotrophic prokaryotes with a plant-like photosynthetic machinery. Because of their short generation times, the ease of their genetic manipulation, and the limited size of their genome and proteome, cyanobacteria are popular model organisms for photosynthetic research. Although the principal mechanisms of photosynthesis are well-known, much less is known about the biogenesis of the thylakoid membrane, hosting the components of the photosynthetic, and respiratory electron transport chain in cyanobacteria. Here we present a detailed proteome analysis of the important model and host organism Synechocystis sp. PCC 6803 under light-activated heterotrophic growth conditions. Because of the mechanistic importance and severe changes in thylakoid membrane morphology under light-activated heterotrophic growth conditions, a focus was put on the analysis of the membrane proteome, which was supported by a targeted lipidome analysis. In total, 1528 proteins (24.5% membrane integral) were identified in our analysis. For 641 of these proteins quantitative information was obtained by spectral counting. Prominent changes were observed for proteins associated with oxidative stress response and protein folding. Because of the heterotrophic growth conditions, also proteins involved in carbon metabolism and C/N-balance were severely affected. Although intracellular thylakoid membranes were significantly reduced, only minor changes were observed in their protein composition. The increased proportion of the membrane-stabilizing sulfoqinovosyl diacyl lipids found in the lipidome analysis, as well as the increased content of lipids with more saturated acyl chains, are clear indications for a coordinated synthesis of proteins and lipids, resulting in stabilization of intracellular thylakoid membranes under stress conditions.
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Affiliation(s)
- Nicole Plohnke
- From the ‡Plant Biochemistry, Faculty of Biology & Biotechnology, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Tobias Seidel
- §Department of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
| | - Uwe Kahmann
- ¶Department of Molecular Cell Biology, Bielefeld University, 33615 Bielefeld, Germany
| | - Matthias Rögner
- From the ‡Plant Biochemistry, Faculty of Biology & Biotechnology, Ruhr-University Bochum, 44780 Bochum, Germany
| | - Dirk Schneider
- §Department of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany;
| | - Sascha Rexroth
- From the ‡Plant Biochemistry, Faculty of Biology & Biotechnology, Ruhr-University Bochum, 44780 Bochum, Germany;
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The Anabaena sp. PCC 7120 Exoproteome: Taking a Peek outside the Box. Life (Basel) 2015; 5:130-63. [PMID: 25782455 PMCID: PMC4390845 DOI: 10.3390/life5010130] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 12/31/2014] [Indexed: 01/13/2023] Open
Abstract
The interest in examining the subset of proteins present in the extracellular milieu, the exoproteome, has been growing due to novel insights highlighting their role on extracellular matrix organization and biofilm formation, but also on homeostasis and development. The cyanobacterial exoproteome is poorly studied, and the role of cyanobacterial exoproteins on cell wall biogenesis, morphology and even physiology is largely unknown. Here, we present a comprehensive examination of the Anabaena sp. PCC 7120 exoproteome under various growth conditions. Altogether, 139 proteins belonging to 16 different functional categories have been identified. A large fraction (48%) of the identified proteins is classified as "hypothetical", falls into the "other categories" set or presents no similarity to other proteins. The evidence presented here shows that Anabaena sp. PCC 7120 is capable of outer membrane vesicle formation and that these vesicles are likely to contribute to the exoproteome profile. Furthermore, the activity of selected exoproteins associated with oxidative stress has been assessed, suggesting their involvement in redox homeostasis mechanisms in the extracellular space. Finally, we discuss our results in light of other cyanobacterial exoproteome studies and focus on the potential of exploring cyanobacteria as cell factories to produce and secrete selected proteins.
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Tonietto A, Petriz BA, Araújo WC, Mehta A, Magalhães BS, Franco OL. Comparative proteomics between natural Microcystis isolates with a focus on microcystin synthesis. Proteome Sci 2012; 10:38. [PMID: 22676507 PMCID: PMC3522533 DOI: 10.1186/1477-5956-10-38] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 05/09/2012] [Indexed: 11/10/2022] Open
Abstract
UNLABELLED BACKGROUND Microcystis aeruginosa is a species of cyanobacteria commonly found in a number of countries and frequently related to animal poisoning episodes due to its capacity to produce the cyanotoxin known as microcystin. Despite vast literature on microcystin structures and their deleterious effects, little is known about its synthesis by cyanobacteria. Therefore, this study used proteomic tools to compare two M. aeruginosa strains, contrasting them for microcystin production. RESULTS 2-DE gels were performed and 30 differential protein spots were chosen. Among them, 11 protein spots were unique in the toxin producing strain and 8 in the non-toxin producing strain, and 14 protein spots were shown on both 2-DE gels but expressed differently in intensity. Around 57% of the tandem mass spectrometry identified proteins were related to energy metabolism, with these proteins being up-regulated in the toxin producing strain. CONCLUSIONS These data suggest that the presence of higher quantities of metabolic enzymes could be related to microcystin metabolism in comparison to the non-toxin producing strain. Moreover, it was suggested that the production of microcystin could also be related to other proteins than those directly involved in its production, such as the enzymes involved in the Calvin cycle and glycolysis.
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Affiliation(s)
- Angela Tonietto
- Centro de Análises Proteômicas e Bioquímicas, Universidade Católica de Brasília, Pós Graduação em Ciências Genômicas e Biotecnologia, SGAN 916 Norte Av, W5, Brasília, DF, Brazil.
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Rowland JG, Simon WJ, Prakash JSS, Slabas AR. Proteomics Reveals a Role for the RNA Helicase crhR in the Modulation of Multiple Metabolic Pathways during Cold Acclimation of Synechocystis sp. PCC6803. J Proteome Res 2011; 10:3674-89. [DOI: 10.1021/pr200299t] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- John G. Rowland
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
| | - William J. Simon
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
| | - Jogadhenu S. S. Prakash
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Antoni R. Slabas
- School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, United Kingdom
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Rupprecht E, Düppre E, Schneider D. Similarities and singularities of three DnaK proteins from the cyanobacterium Synechocystis sp. PCC 6803. PLANT & CELL PHYSIOLOGY 2010; 51:1210-8. [PMID: 20466747 DOI: 10.1093/pcp/pcq074] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In the genome of completely sequenced mesophilic cyanobacterium Synechocystis sp. PCC 6803 three DnaK proteins are encoded, which share a high degree of sequence identity in their N-terminal ATPase region as well as in the adjacent peptide-binding domain. However, as typical for DnaK proteins, the C-termini of the three Synechocystis proteins are highly diverse. To study the functions of the three Synechocystis DnaK proteins in more detail, we have analyzed the abundance of the individual proteins in Synechocystis cells as well as dnaK expression under various stress conditions. The presented results show that all three Synechocystis DnaK proteins interact with the same GrpE nucleotide exchange factor. A comparative analysis indicates that DnaK2 is the most abundant DnaK protein in Synechocystis cells and only the expression of dnaK2 is highly up-regulated under various stress conditions. Finally, we show that a small amino acid motif, which is typically conserved at the very C-terminus of cyanobacterial DnaK3 proteins, is essential for the DnaK3 in vivo function.
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Affiliation(s)
- Eva Rupprecht
- Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 17, D-79104 Freiburg, Germany
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Tabei Y, Okada K, Makita N, Tsuzuki M. Light-induced gene expression of fructose 1,6-bisphosphate aldolase during heterotrophic growth in a cyanobacterium, Synechocystis sp. PCC 6803. FEBS J 2008; 276:187-98. [PMID: 19019077 DOI: 10.1111/j.1742-4658.2008.06772.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Synechocystis sp. PCC 6803 exhibits light-activated heterotrophic growth (LAHG) under dark conditions with glucose as a carbon source. The light activation is remarkable at a late period of photoautotrophic preculture, such as the late-linear and stationary growth phases. To understand the physiological effects of light irradiation and glucose under LAHG conditions, their effects on the expression of soluble proteins were analyzed by means of 2D-PAGE. Various soluble proteins, which were minimal under photoautotrophic preculture conditions, were observed clearly under LAHG conditions, suggesting that proteins were synthesized actively under these conditions. Fructose 1,6-bisphosphate aldolase, one of the glycolytic enzymes, was found to be induced under LAHG conditions on 2D-PAGE. The activity of fructose 1,6-bisphosphate aldolase, which had decreased during photoautotrophic preculture, also increased under LAHG conditions, similar to the mRNA level of the encoding gene, fbaA. In addition, we found that a deletion mutant of sll1330, a putative gene containing a helix-turn-helix DNA-binding motif, could not grow under LAHG conditions, whereas it could grow photoautotrophically. The increases in the protein level of FbaA and fbaA gene expression observed in wild-type cells under LAHG conditions were greatly inhibited in the deletion mutant. These results suggest that the regulation of fbaA gene expression by way of sll1330 is one of the important processes in Synechocystis sp. PCC 6803 under light pulse LAHG conditions.
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Affiliation(s)
- Yosuke Tabei
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, Japan.
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Rupprecht E, Gathmann S, Fuhrmann E, Schneider D. Three different DnaK proteins are functionally expressed in the cyanobacterium Synechocystis sp. PCC 6803. MICROBIOLOGY-SGM 2007; 153:1828-1841. [PMID: 17526840 DOI: 10.1099/mic.0.2007/005876-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Multiple dnaK genes appear to be common in cyanobacteria; the function of the encoded proteins is, however, still elusive. To characterize the dnaK gene family from the cyanobacterium Synechocystis sp. PCC 6803 in detail, genetic analyses were combined with analyses of the expression and localization patterns of the three encoded proteins. While significant expression of all three genes was found, the results obtained clearly indicate physiological differences of the three proteins in vivo, and DnaK2 seems to have a key function in Synechocystis. Expression of DnaK3 appears also to be as essential as expression of DnaK2, whereas the dnaK1 gene was deleted without resulting in any distorted phenotype. In line with a suggested privileged function, expression of DnaK2 altered most significantly after heat shock.
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Affiliation(s)
- Eva Rupprecht
- Fakultät für Biologie, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
| | - Sven Gathmann
- Fakultät für Biologie, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
| | - Eva Fuhrmann
- Fakultät für Biologie, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
| | - Dirk Schneider
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany
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Abstract
The genomic era brought with it the capacity to unlock complex interactions in organisms and biological systems. Currently, by exploiting genomic and associated protein information through in silico analyses, postgenomic research is developing rapidly. This field, which encompasses functional genomics, structural genomics, transcriptomics, pharmacogenomics, proteomics and metabolomics, allows for a systems-wide approach to biological studies. To date, bacterial postgenomic research has focused mainly on a few representative pathogenic species, leaving the vast majority of the microbial community relatively overlooked. Amongst the under-represented microorganisms are the cyanobacteria, which are important for their beneficial natural product production, bioremediation and energy applications. Here, we highlight the current status of cyanobacterial postgenomic research and assess the potential for future metabolic engineering and "cell factory" or "microbial cell" development.
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Affiliation(s)
- Adam M Burja
- Biological and Environmental Systems Group, Department of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK
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Kim YH, Park YM, Kim SJ, Park YI, Choi JS, Chung YH. The role of Slr1443 in pilus biogenesis in Synechocystis sp. PCC 6803: involvement in post-translational modification of pilins. Biochem Biophys Res Commun 2004; 315:179-86. [PMID: 15013443 DOI: 10.1016/j.bbrc.2004.01.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Indexed: 11/29/2022]
Abstract
We isolated a transposon-induced nonmotile mutant of the cyanobacterium Synechocystis sp. PCC 6803. The mutant was revealed to have a Tn5 insertion in the slr1443 gene that showed sequence similarity to a eukaryotic-type protein kinase. Thick pili were not observed on the mutant cell surface under the electron microscope. The slr1443 gene was not involved in transcription or translation of the pilA1 gene encoding pilin, the major component of thick pili. In the mutant, lower molecular mass pilin peptides were detected than in the wild-type. The pilin variant was not truncated at the N- or C-terminus of mature PilA1. The reduced molecular mass may have resulted from insufficient post-translational modification. The amounts of pilin variants were remarkably reduced in the periplasmic and surface fractions. The pilin variants were released into liquid media without being assembled into pili. Our finding suggests that Slr1443 plays an important role in pilus biogenesis at the level of the post-translational modification of pilin.
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Affiliation(s)
- Young Hye Kim
- Proteome Analysis Team, Korea Basic Science Institute, Daejeon 305-333, Republic of Korea
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