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Identification of XcpP domains that confer functionality and specificity to the Pseudomonas aeruginosa type II secretion apparatus
Author(s) -
GérardVincent Ma,
Robert Viviane,
Ball Geneviève,
Bleves Sophie,
Michel Gérard P. F.,
Lazdunski Andrée,
Filloux Alain
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.1365-2958.2002.02991.x
Subject(s) - biology , secretion , pseudomonas aeruginosa , bacterial outer membrane , inner membrane , function (biology) , heterologous , signal peptide , organism , microbiology and biotechnology , model organism , biochemistry , bacteria , peptide sequence , escherichia coli , membrane , genetics , gene
Summary Gram‐negative bacteria have evolved several types of secretion mechanisms to release proteins into the extracellular medium. One such mechanism, the type II secretory system, is a widely conserved two‐step process. The first step is the translocation of signal peptide‐bearing exoproteins across the inner membrane. The second step, the translocation across the outer membrane, involves the type II secretory apparatus or secreton. The secretons are made up of 12–15 proteins (Gsp) depending on the organism. Even though the systems are conserved, hetero‐logous secretion is mostly species restricted. Moreover, components of the secreton are not systematically exchangeable, especially with distantly related microorganisms. In closely related species, two components, the GspC and GspD (secretin) family members, confer specificity for substrate recognition and/or secreton assembly. We used Pseudomonas aeruginosa as a model organism to determine which domains of XcpP (GspC member) are involved in specificity. By constructing hybrids between XcpP and OutC, the Erwinia chrysanthemi homologue, we identified a region of 35 residues that was not exchangeable. We showed that this region might influence the stability of the XcpYZ secreton subcomplex. Remarkably, XcpP and OutC have domains, coiled‐coil and PDZ, respectively, which exhibit the same function but that are structurally different. Those two domains are exchangeable and we provided evidence that they are involved in the formation of homomultimeric complexes of XcpP.