GENETIC-CHARACTERIZATION OF SITE-SPECIFIC INTEGRATION FUNCTIONS OF PHI-AAU2 INFECTING ARTHROBACTER-AUREUS C70

All the essential genetic determinants for site-specific integration o f corynephage phi AAU2 are contained within a 1,756-bp DNA fragment, c arried on the integrative plasmid p5510, and are shown to he functiona l in Escherichia coli. One open reading frame, ORF4, encoding a protei n of 266 amino acids was shown to represent the phi AAU2 integrase. Th e nucleotide sequence of the phi AAU2 attachment site, attP, and the a ttB, attL, and attR sequences in the host ''Arthrobacter aureus'' C70 were determined. Identical nucleotide sequences were shown to be respo nsible for the integration of p5510 in the chromosomes of Corynebacter ium glutamicum, Brevibacterium divaricatum, and B. lactofermentum, and a sequence almost identical to attB was found to be present in these three strains. In contrast to other phage site-specific recombination systems, a plasmid encompassing only int-attP failed to integrate into the host chromosome. This led to the identification of an 800-bp nonc oding region, immediately upstream of int, absolutely required for sit e-specific integration of p5510.