title: sxy-1, a Haemophilus influenzae mutation causing greatly enhanced spontaneous competence.
abstract: A Haemophilus influenzae strain carrying a competence-enhancing mutation (sxy-1) was selected by transformation of a mutagenized culture in exponential growth at low cell density, where spontaneous competence is very rare. Under these conditions, sxy-1 cells spontaneously transformed 100 to 1,000 times more efficiently than wild-type cells. Moreover, sxy-1 cells responded to all known competence-inducing treatments with further increases in transformation frequency. At high cell densities, sxy-1 cells spontaneously developed the level of competence reached by wild-type cells only after maximal induction by transfer to starvation medium. The sxy-1 mutation appears to act early in the sequence of events leading to competence; it increased the competence of cells carrying the early-acting transformation-defective (Tfo-) mutation tfo-98 by as large a factor as it did the competence of wild-type cells, but it had no effect when combined with another early-acting Tfo- mutation (tfo-87) or with the late-acting Tfo- mutation rec-2.
authors.affiliation: Department of Biochemistry, University of British Columbia, Vancouver, Canada.
authors.forename: R J
authors.initials: RJ
authors.lastname: Redfield
mesh_terms: D000693:Anaerobiosis; D000242:Cyclic AMP / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D006193:Haemophilus influenzae / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D009154:Mutation; D010641:Phenotype; D011995:Recombination, Genetic; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; D000242:Cyclic AMP