pcra

PcrA is a DNA helicase encoded by the pcrA gene in many bacteria. It is a member of the SF1 (superfamily 1) helicases and shares sequence and functional similarity with the Escherichia coli UvrD and Rep helicases. PcrA uses ATP hydrolysis to unwind double-stranded DNA and to remodel protein-DNA complexes, translocating along DNA in the 3' to 5' direction.

In cellular processes, PcrA participates in DNA replication, repair, and homologous recombination. It helps resolve conflicts between the replication machinery and transcription, and is involved in transcription-coupled repair by collaborating with the transcription repair coupling factor Mfd and other repair proteins. PcrA also contributes to suppression of R-loop structures that can form during transcription, aiding genome stability.

PcrA homologs are widely distributed in bacteria, with functional conservation across lineages though the essentiality and exact roles may vary by organism. In Bacillus subtilis and related Gram-positive bacteria, PcrA is a prominent helicase that can compensate in part for related helicases in other species, whereas in Gram-negative bacteria UvrD and Rep perform overlapping tasks.

Structurally, PcrA comprises two RecA-like helicase domains that form the catalytic core, flanked by N- and C-terminal regions that mediate protein interactions and regulation. The core contains canonical ATPase and helicase motifs that couple ATP hydrolysis to 3' to 5' translocation and duplex unwinding.