Open AccessHrpB7 from Xanthomonas campestris pv. vesicatoria is an essential component of the type III secretion system and shares features of HrpO/FliJ/YscO family members
Author(s) -
Drehkopf Sabine,
Otten Christian,
Hausner Jens,
Seifert Tanja,
Büttner Daniela
Publication year - 2020
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/cmi.13160
Subject(s) - xanthomonas campestris , biology , chaperone (clinical) , effector , secretion , type three secretion system , cytoplasm , xanthomonas , microbiology and biotechnology , transport protein , protein–protein interaction , biochemistry , bacteria , genetics , virulence , medicine , pathology , gene
The Gram‐negative bacterium Xanthomonas campestris pv. vesicatoria translocates effector proteins via a type III secretion system (T3SS) into eukaryotic cells. The T3SS spans both bacterial membranes and consists of more than 20 proteins, 9 of which are conserved in plant and animal pathogens and constitute the core subunits of the secretion apparatus. T3S in X. campestris pv. vesicatoria also depends on nonconserved proteins with yet unknown function including HrpB7, which contains predicted N‐ and C‐terminal coiled‐coil regions. In the present study, we provide experimental evidence that HrpB7 forms stable oligomeric complexes. Interaction and localisation studies suggest that HrpB7 interacts with inner membrane and predicted cytoplasmic (C) ring components of the T3SS but is dispensable for the assembly of the C ring. Additional interaction partners of HrpB7 include the cytoplasmic adenosinetriphosphatase HrcN and the T3S chaperone HpaB. The interaction of HrpB7 with T3SS components as well as complex formation by HrpB7 depends on the presence of leucine heptad motifs, which are part of the predicted N‐ and C‐terminal coiled‐coil structures. Our data suggest that HrpB7 forms multimeric complexes that associate with the T3SS and might serve as a docking site for the general T3S chaperone HpaB.