RecA-Mediated Induction of Pectin Lyase and Carotovoricin in Erwinia Carotovora Subsp. Carotovora

Abstract

Pectin lyase (PNL) and the bacteriocin, carotovoricin (CTV), were induced in Erwinia carotovora subsp. carotovora (Ecc) strain 71 by the DNA damaging agents mitomycin C, nalidixic acid, and ultraviolet light. These agents, in contrast, were not required for the induction of the pectolytic enzymes pectate lyase and polygalacturonase, which are induced by polygalacturonate or citrus pectin. To determine if the recA product is involved in the expression of pnl or ctv, we cloned the Ecc recA gene, inactivated it by Tn5 insertion, and constructed an Ecc recA::Tn5 strain by site-directed mutagenesis. This RecA- strain resembled RecA- strains of E. coli in that it was highly sensitive to methyl methanesulfonate, nitroquinoline oxide, and UV light. The recA mutation did not affect the production of pectate lyase, polygalacturonase, cellulase and protease, or the ability to cause soft rot of potato tubers. However, in this RecA- strain, unlike the RecA+ parent strain, PNL and CTV were not induced by the DNA damaging agents or detected in infected potato tuber tissue. The RecA+ phenotype, including the inducibility of PNL and CTV, could be restored in the mutants in trans by the recA+ gene from either Ecc or E. coli. We conclude that in Ecc the recA product is required in the induction of PNL and CTV.