Physical Map of Caulobacter Crescentus Bacteriophage Phi Cd1 DNA

A restriction map of the Caulobacter crescentus bacteriophage phi Cd1 genome was constructed by using the restriction endonucleases HindIII and HpaI. A total of 12 fragments, ranging in molecular weight from 7.7 X 10(6) to 0.25 X 10(6), were produced by HindIII, and 7 fragments, ranging in molecular weight from 9.0 X 10(6) to 0.24 X 10(6), were generated by HpaI. The molecular weight of the genome was estimated to be approximately 28.8 X 10(6) on the basis of the relative electrophoretic mobilities of the restriction fragments. The relative order of the cleavage fragments was determined by specific cleavage of isolated restriction fragments, terminal labeling of both the whole genome and isolated fragments, and hybridization of isolated fragments to restriction fragments generated by other restriction enzymes. The genome of phi Cd1 was found to be terminally repetitive, and analysis of previously determined in vivo and in vitro RNA transcripts showed that the restriction map could be oriented such that transcription began on the left and proceeded to the right end of the genome.