Roles of the Minor Pseudopilins, XpsH, XpsI and XpsJ, in the Formation of XpsG-Containing Pseudopilus in Xanthomonas campestris pv. Campestris
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Due to their similarity to type IV pilus (Tfp) subunits, the pseudopilins, XpsG, -H, -I, -J and -K, have been predicted to form a pilus-like structure in the type II secretion (T2S) pathway. While overexpression of GspG can result in the formation of bundle structures, the functions of other pseudopilin are not known yet. In this study, we investigate the mutual interaction among the pseudopilins and characterize the specialized minor pseudopilin, XpsJ. By using gel filtration and Ni-NTA affinity chromatography, a linearly ordered interactive relationship is revealed among the four pseudopilins, XpsG-XpsI-XpsH-XpsJ. Notably, unlike the mutant XpsJ194 staying in the inner membrane, wild type XpsJ stayed in the outer membrane and blocked the extension of overexpressed XpsG to outside of the cell. By analogy with the Type I pilus structures, we hypothesize that the XpsH and XpsI might act as an adaptor to connect XpsJ with the major pseudopilin XpsG, and XpsJ might act as a tip to restrict the out-growth of XpsG in the pilus-like structure of the T2S pathway.
Keywordsmajor pseudopilin minor pseudopilin tip type IV pili type I pili type II secretion pathway
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- 18.Lee, H.M., Wang, K.C., Liu, Y.L., Yew, H.Y., Chen, L.Y., Leu, W.M., Chen, D.C., Hu, N.T. (2000) "Association of the cytoplasmic membrane protein XpsN with the outer membrane protein XpsD in the type II protein secretion apparatus of Xanthomonas campestris pv. campestris" J. Bacteriol. 182: 1549-1557CrossRefPubMedGoogle Scholar
- 20.Brinton, C.C., Jr. (1965) "The structure, function, synthesis and genetic control of bacterial pili and a molecular model for DNA and RNA transport in gram negative bacteria" Trans. NY. Acad. Sci. 27: 1003-1054Google Scholar