Open AccessFlagellar Localization of a Helicobacter pylori Autotransporter Protein
Author(s) -
Ja. Radin,
Jennifer A. Gaddy,
Christian González-Rivera,
John T. Loh,
Holly M. Scott Algood,
Timothy L. Cover
Publication year - 2013
Publication title -
mbio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.562
H-Index - 121
eISSN - 2161-2129
pISSN - 2150-7511
DOI - 10.1128/mbio.00613-12
Subject(s) - flagellum , microbiology and biotechnology , biology , mutant , helicobacter pylori , bacterial outer membrane , bacteria , effector , motility , secretory protein , pathogenic bacteria , secretion , gene , escherichia coli , genetics , biochemistry
Helicobacter pylori contains four genes that are predicted to encode proteins secreted by the autotransporter (type V) pathway. One of these, the pore-forming toxin VacA, has been studied in great detail, but thus far there has been very little investigation of three VacA-like proteins. We show here that all three VacA-like proteins are >250 kDa in mass and localized on the surface ofH. pylori . The expression of the threevacA -like genes is upregulated duringH. pylori colonization of the mouse stomach compared toH. pylori growthin vitro , and a wild-typeH. pylori strain outcompeted each of the three corresponding isogenic mutant strains in its ability to colonize the mouse stomach. One of the VacA-like proteins localizes to a sheath that overlies the flagellar filament and bulb, and therefore, we designate it FaaA (flagella-associated autotransporter A). In comparison to a wild-typeH. pylori strain, an isogenicfaaA mutant strain exhibits decreased motility, decreased flagellar stability, and an increased proportion of flagella in a nonpolar site. The flagellar localization of FaaA differs markedly from the localization of other known autotransporters, and the current results reveal an important role of FaaA in flagellar localization and motility.IMPORTANCE The pathogenesis of most bacterial infections is dependent on the actions of secreted proteins, and proteins secreted by the autotransporter pathway constitute the largest family of secreted proteins in pathogenic Gram-negative bacteria. In this study, we analyzed three autotransporter proteins (VacA-like proteins) produced byHelicobacter pylori , a Gram-negative bacterium that colonizes the human stomach and contributes to the pathogenesis of gastric cancer and peptic ulcer disease. We demonstrate that these three proteins each enhance the capacity ofH. pylori to colonize the stomach. Unexpectedly, one of these proteins (FaaA) is localized to a sheath that overliesH. pylori flagella. The absence of FaaA results in decreasedH. pylori motility as well as a reduction in flagellar stability and a change in flagellar localization. The atypical localization of FaaA reflects a specialized function of this autotransporter designed to optimizeH. pylori colonization of the gastric niche.