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Genetic dissection of the Ralstonia solanacearum hrp gene cluster reveals that the HrpV and HrpX proteins are required for Hrp pilus assembly
Author(s) -
Gijsegem Frédérique Van,
Vasse Jacques,
Rycke Riet De,
Castello Philippe,
Boucher Christian
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02936.x
Subject(s) - ralstonia solanacearum , pilus , biology , pilin , secretion , mutant , effector , gene cluster , type three secretion system , gene , bacteria , microbiology and biotechnology , genetics , escherichia coli , biochemistry
Summary In both plant and mammalian Gram‐negative pathogenic bacteria, type III secretion systems (TTSSs) play a crucial role in interactions with the host. All these systems share conserved proteins (called Hrc in plant pathogens), but each bacterium also produces a variable number of additional type III proteins either unique or with counterparts only in a limited number of related systems. In order to investigate the role of the different proteins encoded by the hrp gene cluster of the phytopathogenic bacterium Ralstonia solanacearum , non‐polar mutants in all hrp genes (except for hrcQ ) were analysed for their interactions with plants, their ability to secrete the PopA protein and their production of the Hrp pilus. In addition to Hrc proteins and the HrpY major component of the Hrp pilus, four additional Hrp proteins are indispensable for type III secretion and for interactions with plants. We also provide evidence that hrpV and hrpX mutants can still target the HrpY pilin outside the bacterial cell but are impaired in the production of Hrp pili, indicating that HrpV and HrpX proteins are involved in the assembly of this appendage.