Identification of a putative RNA helicase in E.coli.

The human p68 protein, an SV40 large T related antigen, is an RNA dependent ATPase and RNA helicase. It belongs to a new large and highly conserved gene family, the DEAD box proteins, whose members are involved in a variety of processes requiring manipulation of RNA secondary structure such as translation and splicing. Multiple DEAD box genes are present in S.cerevisiae, but only one has previously been described in E.coli. Low stringency screening of an E.coli genomic library with a p68 cDNA probe led to the identification of dbpA, a new E.coli DEAD box gene located at 29.6 minutes on the W3110 chromosome. We report here the nucleotide and deduced amino acid sequences of the gene. We have overexpressed dbpA from its own promoter on a high copy number plasmid and identified the gene product as a approximately 50 kD protein by immunoblotting with an anti-DEAD antibody.