Article
- The EMBO Journal (1998) 17, 3640 - 3650
- doi:10.1093/emboj/17.13.3640
Overlapping functions of components of a bacterial Sec-independent protein export pathway
Frank Sargent1,2, Erik G. Bogsch3, Nicola R. Stanley1,2, Margaret Wexler1,2, Colin Robinson3, Ben C. Berks2 and Tracy Palmer1,2
- Nitrogen Fixation Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, UK
- Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
Correspondence to:
Tracy Palmer, E-mail: PALMER@BBSRC.AC.UK
Received 14 April 1998; Accepted 29 April 1998
Abstract
We describe the identification of two Escherichia coli genes required for the export of cofactor-containing periplasmic proteins, synthesized with signal peptides containing a twin arginine motif. Both gene products are homologous to the maize HCF106 protein required for the translocation of a subset of lumenal proteins across the thylakoid membrane. Disruption of either gene affects the export of a range of such proteins, and a complete block is observed when both genes are inactivated. The Sec protein export pathway was unaffected, indicating the involvement of the gene products in a novel export system. The accumulation of active cofactor-containing proteins in the cytoplasm of the mutant strains suggests a role for the gene products in the translocation of folded proteins. One of the two HCF106 homologues is encoded by the first gene of a four cistron operon, tatABCD, and the second by an unlinked gene, tatE. A mutation previously assigned to the hcf106 homologue encoded at the tatABCD locus, mttA, lies instead in the tatB gene.
Keywords:
- hydrogenases,
- molybdoenzymes,
- periplasm,
- Sec-independent protein export,
- twin arginine transfer peptide
