Open AccessThe torYZ ( yecK bisZ ) Operon Encodes a Third Respiratory Trimethylamine N -Oxide Reductase in Escherichia coli
Author(s) -
Stéphanie Gon,
JeanClaude Patte,
Vincent Méjean,
Chantal IobbiNivol
Publication year - 2000
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.182.20.5779-5786.2000
Subject(s) - operon , biology , escherichia coli , reductase , biochemistry , periplasmic space , gene , cytochrome , microbiology and biotechnology , enzyme
ThebisZ gene ofEscherichia coli was previously described as encoding a minor biotin sulfoxide (BSO) reductase in addition to the main cytoplasmic BSO reductase, BisC. In this study,bisZ has been renamedtorZ based on the findings that (i) thetorZ gene product, TorZ, is able to reduce trimethylamineN -oxide (TMAO) more efficiently than BSO; (ii) although TorZ is more homologous to BisC than to the TMAO reductase TorA (63 and 42% identity, respectively), it is located mainly in the periplasm as is TorA; (iii)torZ belongs to thetorYZ operon, and the first gene,torY (formerlyyecK ), encodes a pentahemicc -type cytochrome homologous to the TorC cytochrome of the TorCAD respiratory system. Furthermore, thetorYZ operon encodes a third TMAO respiratory system, with catalytic properties that are clearly different from those of the TorCAD and the DmsABC systems. ThetorYZ and thetorCAD operons may have diverged from a common ancestor, but, surprisingly, notorD homologue is found in the sequences aroundtorYZ . Moreover, thetorYZ operon is expressed at very low levels under the conditions tested, and, in contrast totorCAD , it is not induced by TMAO or dimethyl sulfoxide.