Primary structure and features of the genome of the Lactobacillus gasseri temperate bacteriophage φadh

Abstract

The complete DNA sequence of the Lactobacillus (Lb.) gasseri temperate phage φadh was determined. The linear and double-stranded genome consists of 43.785 bp with a G+C content of 35.3% and 3′ protruding cohesive ends of 12 nt. Sixty-two possible ORFs were identified. On the basis of homology comparisons, some of them could be assigned to possible functions, such as a helicase, a nucleic acid polymerase and a protease. In a non-coding area of the φadh genome, structural features of a potential replication origin were detected. After subcloning, this region was functional as a replicon in Lb. gasseri and Lactococcus lactis. N-terminal aa sequencing and electron microscopic analysis of intact and defective phage particles enabled the identification of two capsid protein genes. One of their products, the major head protein, seems to be processed on the posttranslational level.