CHARACTERIZATION OF THE GENES ENCODING INTEGRATIVE AND EXCISIVE FUNCTIONS OF LACTOBACILLUS PHAGE OGLE - CLONING, SEQUENCE-ANALYSIS, AND EXPRESSION IN ESCHERICHIA-COLI

ogle is a temperate phage of the Lactobacillus strain Gle. The phage-h ost junctions attR and attL cloned from the lysogen have a 24-bp commo n (core) sequence implicated in recombination. DNA sequencing analysis of a 5.2-kbp SacI fragment of the ogle phage genome (42.5 kbp) reveal ed two possible open reading frames (ORF), xis and int, and the phage attachment (recombination) site (attP), whose 24-bp sequence is identi cal to the core sequence detected in attR and attL. The deduced int pr oduct (Int) is a basic protein of 391 amino acids with an estimated pI of 9.70o, and significantly resembles other presumed integrases encod ed by the Lactobacillus and Lactococcus phages including oadh and oLC3 , as well as the Escherichia coli phages such as lambda. The predicted ogle xis protein (Xis) is small and very acidic (66 amino acids; pI 4 .55), and shows a resemblance (32% overall identity) with a putative e xcisionase encoded by the Staphylococcus phage o11. The ogle Int with a deduced molecular mass of 45.5 kDa was overproduced in E. coli cells , and electrophoretically analyzed.