title: Essential bacterial helicases that counteract the toxicity of recombination proteins.
abstract: PcrA, Rep and UvrD are three closely related bacterial helicases with a DExx signature. PcrA is encoded by Gram-positive bacteria and is essential for cell growth. Rep and UvrD are encoded by Gram-negative bacteria, and mutants lacking both helicases are also not viable. To understand the non-viability of the helicase mutants, we characterized spontaneous extragenic suppressors of a Bacillus subtilis pcrA null mutation. Here we report that one of these suppressors maps in recF and that previously isolated mutations in B.subtilis recF, recL, recO and recR, which belong to the same complementation group, all suppress the lethality of a pcrA mutation. Similarly, recF, recO or recR mutations suppress the lethality of the Escherichia coli rep uvrD double mutant. We conclude that RecFOR proteins are toxic in cells devoid of PcrA in Gram-positive bacteria, or Rep and UvrD in Gram-negative bacteria, and propose that the RecFOR proteins interfere with an essential cellular process, possibly replication, when DExx helicases PcrA, or Rep and UvrD are absent.
authors.affiliation: Laboratoire de Génétique Microbienne, INRA, 78352 Jouy en Josas cedex, France. petit@necker.fr
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Petit
authors.forename: Dusko
authors.initials: D
authors.lastname: Ehrlich
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D009154:Mutation; D009876:Operon / Q000235:genetics; D011995:Recombination, Genetic; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C084217:pcrA protein, Bacteria; C506744:rep protein, E coli; D000251:Adenosine Triphosphatases; C506746:UvrD protein, E coli; D004265:DNA Helicases