title: The proteome of Shigella flexneri 2a 2457T grown at 30 and 37 degrees C.
abstract: To upgrade the proteome reference map of Shigella flexneri 2a 2457T, the protein expression profiles of log phase and stationary phase cells grown at 30 and 37 degrees C were thoroughly analyzed using multiple overlapping narrow pH range (between pH 4.0 and 11.0) two-dimensional gel electrophoresis. A total of 723 spots representing 574 protein entries were identified by MALDI-TOF/TOF MS, including the majority of known key virulence factors. 64 hypothetical proteins and six misannotated proteins were also experimentally identified. A comparison between the four proteome maps showed that most of the virulence-related proteins were up-regulated at 37 degrees C, and the differences were more notable in stationary phase cells, suggesting that the expressions of these virulence factors were not only controlled by temperature but also controlled by the nutrients available in the environment. The expression patterns of some virulence-related genes under the four different conditions suggested that they might also be regulated at the post-transcriptional level. A further significant finding was that the expression of the protein ArgT was dramatically up-regulated at 30 degrees C. The results of semiquantitative RT-PCR analysis showed that expression of argT was not regulated at the transcriptional level. Therefore, we carried out a series of experiments to uncover the mechanism regulating ArgT levels and found that the differential expression of ArgT was due to its degradation by a periplasmic protease, HtrA, whose activity, but not its synthesis, was affected by temperature. The cleavage site in ArgT was between position 160 (Val) and position 161 (Ala). These results may provide useful insights for understanding the physiology and pathogenesis of S. flexneri.
authors.affiliation: Beijing Institute of Biotechnology, State Key Laboratory of Pathogen and Biosecurity, 100071 Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhu
authors.forename: Ge
authors.initials: G
authors.lastname: Zhao
authors.forename: Robert
authors.initials: R
authors.lastname: Stein
authors.forename: Xuexue
authors.initials: X
authors.lastname: Zheng
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: Na
authors.initials: N
authors.lastname: Shang
authors.forename: Xin
authors.initials: X
authors.lastname: Bu
authors.forename: Xiankai
authors.initials: X
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Erling
authors.initials: E
authors.lastname: Feng
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Xuemin
authors.initials: X
authors.lastname: Zhang
authors.forename: Qinong
authors.initials: Q
authors.lastname: Ye
authors.forename: Peitang
authors.initials: P
authors.lastname: Huang
authors.forename: Ming
authors.initials: M
authors.lastname: Zeng
authors.forename: Hengliang
authors.initials: H
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism; D019897:Periplasm / Q000378:metabolism; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D011685:Purine Nucleotides / Q000096:biosynthesis; D012015:Reference Standards; D012763:Shigella flexneri / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism* / Q000472:pathogenicity; D013696:Temperature; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D026905:Amino Acid Transport Systems; D001426:Bacterial Proteins; D020543:Proteome; D011685:Purine Nucleotides; D037521:Virulence Factors; D010447:Peptide Hydrolases