Affiliations: Department of Studies in Microbiology, University of
Mysore, Manasagangothri, Mysore, India | Chair of Microbiology, Biocenter, University of
Würzburg, Würzburg, Germany
Abstract: Thiol:disulfide redox metabolism (TDRM) is a central metabolic
network in all living cells. However, numerous proteins with different
biochemical functions and several structural domains are involved, making it
not trivial to identify and annotate its constituents in sequenced genomes. We
developed an uncomplicated approach to solve the problem using existing
web-based tools and public databases with the gram-positive bacterium
Listeria monocytogenes EGD-e as a model organism. A pattern search for the
Cys-Xaa-Xaa-Cys (CXXC) motif – a hallmark of TDRM proteins – in the genome
sequence of the bacterium yielded 156 proteins. After initial refinement by
protein and domain analysis, 14 candidate proteins remained. Subsequent
detailed analyses, supported by modeling of 3D structures and data integration
yielded 6 thioredoxin-like proteins plus thioredoxin reductase, glutaredoxin,
one redox-sensitive regulator, one peptide methionine reductase – all typical
TDRM constituents – and three putative novel components of the TDRM. For all
14 proteins orthologues were found in other Listeria species. Homology
searches and phylogenetic analyses showed that related proteins are present
mainly in other Firmicutes. This fast approach required minimal
resources. It is immediately applicable to any genome with appropriate
modifications and should be practicable also for other conserved, functionally
important amino acid motifs.
Keywords: CXXC motif, 3D structure, L. monocytogenes EGD-e, phylogeny, redox, thiol:disulfide
