DNA sequence analysis of prm-mutations of coliphage lambda.

Nucleotide sequence changes associated with mutation of the prm promoter of bacteriophage lambda have been determined. Prm-mutations have been assigned to two classes. Class I mutations appear to affect the interaction of RNA polymerase with prm; six class I mutations affect four sites, located 14, 33, 38, and 39 bp preceding the prm transcription startpoint. Class II mutations appear to owe their Prm-phenotype to a change in OR, which could prevent activation of prm by repressor. All three class II mutations are in OR 1.