NUCLEOTIDE-SEQUENCE AND TRANSCRIPTION OF THE LEFT EARLY REGION OF STREPTOCOCCUS-PNEUMONIAE BACTERIOPHAGE-CP-1 CODING FOR THE TERMINAL PROTEIN AND THE DNA-POLYMERASE

Cp-1 is a small virulent bacteriophage infecting Streptococcus pneumon iae. It has a linear, double-stranded genome of about 19 kb that repli cates by a protein-priming mechanism. We have determined the nucleotid e sequence of the leftmost 4780 bp of the DNA of this bacteriophage; c omputer analysis revealed that this fragment contains seven open readi ng frames (ORFs) which could encode polypeptides containing more than 50 amino acids. The ORFs are clustered in two groups separated by nonc oding intergenic regions. Two of these ORFs code for the terminal prot ein and a specific DNA polymerase that participate in the replication of the DNA. The predicted amino acid sequence of the terminal protein shows significant similarity with the terminal protein of Bacillus sub tilis phage phi 29, and Cp-1 DNA polymerase is homologous to the subgr oup of eukaryotic-type DNA polymerases that use a protein as a primer. Combined Northern blots and primer extension experiments have allowed us to map the 5' initiation sites of left early transcripts. These st udies revealed that transcripts elongate from left to right and identi fied the left early promoters. (C) 1995 Academic Press, Inc.