Escherichia coli cold shock protein CsdA effects an increase in septation and the resultant formation of coccobacilli at low temperature.

Bacterial shape is controlled by peptidoglycan assembly along the lateral wall and at the septum site. In contrast to rods at 37°C, the wild-type strain formed coccobacilli at 12°C, indicating a prevailing shift toward septal peptidoglycan synthesis at low temperature. Escherichia coli cold shock protein CsdA is a DEAD-box RNA helicase with an extended variable region at the carboxyl terminus.

Mutational analysis of the Escherichia coli DEAD box protein CsdA.

The Escherichia coli cold shock protein CsdA is a member of the DEAD box family of ATP-dependent RNA helicases, which share a core of nine conserved motifs. The DEAD (Asp-Glu-Ala-Asp) motif for which this family is named has been demonstrated to be essential for ATP hydrolysis. We show here that CsdA exhibits in vitro ATPase and helicase activities in the presence of short RNA duplexes with either 3' or 5' extensions at 15 degrees C.