The SecB chaperone is bifunctional in Serratia marcescens: SecB is involved in the Sec pathway and required for HasA secretion by the ABC transporter.

ABSTRACT: HasA is the secreted hemophore of the heme acquisition system (Has) of Serratia marcescens. It is secreted by a specific ABC transporter apparatus composed of three proteins: HasD, an inner membrane ABC protein; HasE, another inner membrane protein; and HasF, a TolC homolog. Except for HasF, the structural genes of the Has system are encoded by an iron-regulated operon. In previous studies, this secretion system has been reconstituted in Escherichia coli, where it requires the presence of the SecB chaperone, the Sec pathway-dedicated chaperone. We cloned and inactivated the secB gene from S. marcescens. We show that S. marcescens SecB is 93% identical to E. coli SecB and complements the secretion defects of a secB mutant of E. coli for both the Sec and ABC pathways of HasA secretion. In S.

SUBMITTER: Sapriel G 

PROVIDER: S-EPMC141835 | biostudies-literature | 2003 Jan

REPOSITORIES: biostudies-literature