The gene encoding a periplasmic deoxyribonuclease from Aeromonas hydrophila

A gene encoding a deoxyribonuclease, dnsH, was cloned from Aeromonas hydrop hila JMP636. The predicted mature protein was very similar to the previousl y described extracellular Dns from this organism and an N-terminal region c orresponding to a large putative signal sequence was predicted for the JMP6 36 protein. Inactivation of dnsH demonstrated that the DnsH protein was nor present extracellularly in this strain. As DnsH degraded plasmid DNA and w as believed to have a periplasmic location, a dnsH mutant was constructed t o determine whether electroporation of A. hydrophila with plasmid DNA could be achieved. No transformants were detected. From SDS-PAGE studies, at lea st two additional DNases remain to be characterised from A. hydrophila JMP6 36. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.