DksA2, a zinc-independent structural analog of the transcription factor DksA.

Transcription factor DksA contains a four-Cys Zn(2 +)-finger motif thought to be responsible for structural integrity and the relative disposition of its domains. Pseudomonas aeruginosa encodes an additional DksA paralog (DksA2) that is expressed selectively under Zn(2+) limitation. Although DksA2 does not bind Zn(2+), it complements the Escherichia coli dksA deletion and has similar effects on transcription in vitro. In this study, structural and biochemical analyses reveal that DksA2 has a similar fold, domain structure and RNA polymerase binding properties to those of the E. coli DksA despite the lack of the stabilizing metal ion.