Molecular organization of the xcp gene cluster in Pseudomonas putida: absence of an xcpX (gspK) homologue

A DNA fragment containing rep (gsp) gene homologues, required for extracell ular protein secretion by the general secretory pathway (GSP) in Various Gr am-negative bacteria, was cloned from Pseudomonas putida (Pp) strain WCS358 and sequenced. The results presented here and those previously reported (d e Groot, A., Krijger, J.-J., Filloux, A., Tommassen, J., 1996). Characteriz ation of type II protein secretion (xcp) genes in the plant growth-stimulat ing Pseudomonas putida, strain WCS358 Mel. Gen. Genet. 250, 491-504) comple te the sequence of the rep gene cluster of Pp. Unlike that of Pseudomonas a eruginosa (Pa), the rep gene cluster of Pp contains a gspN homologue. More surprisingly, in contrast to all known gsp gene clusters, the xcpX (gspK) h omologue is not found. In addition, genes flanking the rep cluster of Pp ar e not related to those flanking the rep genes of Pa. Overall, the rep gene products of Pp are as much related to those of Pa as to gsp gene products o f enterobacterial species, suggesting that the rep clusters of Pp and Pa ha ve evolved separately. (C) 1999 Elsevier Science B.V. All rights reserved.