Archives of Microbiology

, 191:519

A genetic analysis of in vivo selenate reduction by Salmonella enterica serovar Typhimurium LT2 and Escherichia coli K12

Original Paper

DOI: 10.1007/s00203-009-0478-7

Cite this article as:
Guymer, D., Maillard, J. & Sargent, F. Arch Microbiol (2009) 191: 519. doi:10.1007/s00203-009-0478-7

Abstract

The twin-arginine transport (Tat) system is dedicated to the translocation of folded proteins across the bacterial cytoplasmic membrane. Proteins are targeted to the Tat system by signal peptides containing a twin-arginine motif. In Salmonella enterica serovar Typhimurium and Escherichia coli many Tat substrates are known or predicted to bind a molybdenum cofactor in the cytoplasm prior to export. In the case of N- and S-oxide reductases, co-ordination of molybdenum cofactor insertion with protein export involves a ‘Tat proofreading’ process where chaperones of the TorD family bind the signal peptides, thus preventing premature export. Here, a genetic approach was taken to determine factors required for selenate reductase activity in Salmonella and E. coli. It is reported for both biological systems that an active Tat translocase and a TorD-like chaperone (DmsD) are required for complete in vivo reduction of selenate to elemental red selenium. Further mutagenesis and in vitro biophysical experiments implicate the SalmonellaynfE gene product, and the E. coli YnfE and YnfF proteins, as putative Tat-targeted selenate reductases.

Keywords

Enteric bacteriaBacterial respirationTwin-arginine translocation pathwayMolybdo-enzymesSelenate reductaseMolecular chaperoneMutagenesisIsothermal titration calorimetry

Abbreviations

TMAO

Trimethylamine N-oxide

Tat

Twin-arginine translocation

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Division of Molecular Microbiology, College of Life SciencesUniversity of DundeeDundeeScotland, UK
  2. 2.ENAC-ISTE/Laboratoire de Biotechnologie Environnementale (LBE)EPF LausanneLausanneSwitzerland