SEQUENCE-ANALYSIS OF PLASMID PRA2 FROM PSEUDOMONAS-ALCALIGENES NCIB-9867 (P25X) REVEALS A NOVEL REPLICATION REGION

The replication region of plasmid pRA2 from Pseudomonas alcaligenes NC IB 9867 (strain P25X) was localized within a 5.9-kbp DNA fragment and its sequence was determined. An interesting feature of the sequence is the presence of a 1.3-kbp region containing seven, highly conserved, direct repeats of 72 bp in length. The pRA2 replication region has two open reading frames (ORFs). ORF1 appeared to be essential for replica tion and had the potential to encode a novel 30-kDa protein with a pre dicted helix-turn-helix motif located at the C-terminal end. ORF2 was not essential for replication and may encode for a 37-kDa protein whic h shares 41% and 27% amino acid sequence identity to the KfrA proteins from plasmids RK2 and R751, respectively. The essential region of rep lication was narrowed down to 2819 nucleotides and included four of th e seven 72-bp direct repeats, a potential DnaA-binding site and ORF1. (C) 1998 Federation of European Microbiological Societies. Published b y Elsevier Science B.V.