The ChrT gene encodes a
chromate reductase enzyme which catalyzes the reduction of
Cr(VI). The
chromate reductase is also known as
flavin mononucleotide (
FMN) reductase (
FMN_red). The aim of the present study was to clone the full-length ChrT
DNA from Serratia sp. CQMUS2 and analyze the deduced amino acid sequence and three-dimensional structure. The putative ChrT gene fragment of Serratia sp. CQMUS2 was isolated by polymerase chain reaction (PCR), according to the known
FMN_red gene sequence from Serratia sp. AS13. The flanking sequences of the ChrT gene were obtained by high efficiency TAIL-PCR, while the full-length gene of ChrT was cloned in Escherichia coli for subsequent sequencing. The nucleotide sequence of ChrT was submitted onto GenBank under the accession number, KF211434. Sequence analysis of the gene and
amino acids was conducted using the Basic Local Alignment Search Tool, and open reading frame (ORF) analysis was performed using ORF Finder software. The ChrT gene was found to be an ORF of 567 bp that encodes a 188-amino
acid enzyme with a calculated molecular weight of 20.4 kDa. In addition, the ChrT
protein was hypothesized to be an
NADPH-dependent
FMN_red and a member of the flavodoxin-2 superfamily. The amino acid sequence of ChrT showed high sequence similarity to the
FMN reductase genes of Klebsiella
pneumonia and Raoultella ornithinolytica, which belong to the flavodoxin-2 superfamily. Furthermore, ChrT was shown to have a 85.6% similarity to the three-dimensional structure of Escherichia coli ChrR, sharing four common
enzyme active sites for
chromate reduction. Therefore, ChrT gene cloning and
protein structure determination demonstrated the ability of the gene for
chromate reduction. The results of the present study provide a basis for further studies on ChrT gene expression and
protein function.