Mazurkiewicz Piotr, Thomas Jerry, Thompson Jessica A, Liu Mei, Arbibe Laurence, Sansonetti Philippe, Holden David W
Centre for Molecular Microbiology and Infection, Imperial College London, Armstrong Road, London SW7 2AZ, UK.
Mol Microbiol. 2008 Mar;67(6):1371-83. doi: 10.1111/j.1365-2958.2008.06134.x. Epub 2008 Feb 15.
SpvC is encoded by the Salmonella virulence plasmid. We have investigated the biochemical function of SpvC and the mechanism by which it is secreted by bacteria and translocated into infected macrophages. We constructed a strain carrying a deletion in spvC and showed that the strain is attenuated for systemic virulence in mice. SpvC can be secreted in vitro by either the SPI-1 or SPI-2 type III secretion systems. Cell biological and genetic experiments showed that translocation of the protein into the cytosol of macrophages by intracellular bacteria is dependent on the SPI-2 T3SS. Using antibodies specific to phospho-amino acids and mass spectrometry we demonstrate that SpvC has phosphothreonine lyase activity on full-length phospho-Erk (pErk) and a synthetic 13-amino-acid phospho-peptide containing the TXY motif. A Salmonella strain expressing spvC from a plasmid downregulated cytokine release from infected cells.
SpvC由鼠伤寒沙门氏菌毒力质粒编码。我们研究了SpvC的生化功能以及它被细菌分泌并转运到受感染巨噬细胞中的机制。我们构建了一个spvC基因缺失的菌株，并表明该菌株在小鼠体内的全身毒力减弱。SpvC可以在体外通过SPI-1或SPI-2 III型分泌系统分泌。细胞生物学和遗传学实验表明，细胞内细菌将该蛋白转运到巨噬细胞胞质溶胶中依赖于SPI-2 III型分泌系统。使用磷酸氨基酸特异性抗体和质谱分析，我们证明SpvC对全长磷酸化细胞外信号调节激酶（pErk）和一个含有TXY基序的合成13氨基酸磷酸肽具有磷酸苏氨酸裂解酶活性。一个从质粒表达spvC的沙门氏菌菌株下调了受感染细胞的细胞因子释放。
