Mapping of Promoter Sites on the Genome of Bacteriophage M13

With the aid of transcription studies on restriction fragments of bacteriophage M13 DNA it has been demonstrated that at least eight promoter sites are located on the M13 genome. Five of these promoters initiate the synthesis of RNA chains which contain at their 5′‐terminal end pppG (G promoters), while the other three promoters initiate RNA chains which start exclusively with pppA (A promoters). The positions of these promoter sites on the physical map are: 0.82 (G 0.82 ), 0.88 ((G 0.88 ). 0.94 (G 0.94 ), 0.01 (G 0.01 ), 0.08 (G 0 08 ), 0.36 (A 0 36 ), 0.51 (A 0.51 ) and 0.56 (A 0.56 ). The G promoters were found to be clustered within a distance of one‐third of the genome length from the central termination site for transcription (map position 0.77). The A promoters, however, were found at greater distances from this termination signal. Based upon the incorporation of [γ‐ 32 P]ATP or [γ‐ 32 P]GTP, the capacity of these promoters to initiate the synthesis of RNA chains varies. The strongest G promoters are G 0.82 , G 0.94 and G 0.08 and the strongest A promoter is A 0.36 . As judged from their position on the genetic map, it is postulated that two promoters. namely G 0.94 and G 0.01 , are located within gene II. The other promoters are most probably located inunediately in front of the gene VIII/VII boundary (G 0.82 ), and immediately in front of gene V (G 0 88 ), gene II (G 0.08 ), gene IV (A 0.36 ), gene I (A 0.51 ) and gene VI (A 0.56 ). No evidence has been obtained so fou‐ for the existence of a promoter immediately in front of gene III.