The bacterial replicative helicase DnaB evolved from a RecA duplication.

摘要: The RecA/Rad51/DCM1 family of ATP-dependent recombinases plays a crucial role in genetic recombination and double-stranded DNA break repair Archaea, Bacteria, Eukaryota. DnaB is the replication fork helicase all Bacteria. We show here that shares significant sequence similarity with RecA Rad51/DMC1 two other related families ATPases, Sms KaiC. conserved region spans entire ATP- DNA-binding domain consists about 250 amino acid residues includes 7 distinct motifs. Comparison three-dimensional structure Escherichia coli phage T7 (gp4) reveals area conservation central parallel beta-sheet most connecting helices loops as well smaller amino-terminal helix carboxy-terminal beta-meander. Additionally, we animals, plants, malarial Plasmodium but not Saccharomyces cerevisiae encode previously undetected homolog might function mitochondria. from Arabidopsis also contains DnaG-primase nematode seems to contain an inactivated version primase. This organization reminiscent bacteriophage primases-helicases suggests have been horizontally introduced into nuclear eukaryotic genome via vector. hypothesize originated duplication RecA-like ancestor after divergence bacteria Archaea eukaryotes, which indicates helicases Bacteria Archaea/Eukaryota evolved independently.