ISSN:
0091-7419
Keywords:
Life Sciences
;
Molecular Cell Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Phage P22 is known to have a linear duplex chromosome which is circularly permuted and terminally repeated. The propagation of these features of the mature phage DNA is accounted for by the fact that phage DNA lengths (headfuls) are cut from an intracellular intermediate form of phage DNA several phage genomes in length (concatemer) as first suggested by Streisinger. Studies with mutant phages show that cutting of concatemer DNA is intimately connected to the morphogenesis of the phage head.We have also found, by constructing a partial denaturation map of mature P22 DNA, that circular permutation in P22 DNA is restricted: all of the ends of the mature DNA fall within 20% of each other on the physical map. The limited distribution of ends can be explained by Streisinger's “headful” packaging model with the additional specifications that: a. the intracellular precursor DNA is no longer than ten times the length of mature phage DNA; b. encapsulation of DNA starts at a unique site; c. encapsulation proceeds sequentially therefrom.This model is supported by the distribution of molecular ends in denaturation maps of two deletion phage DNAs. We found, as expected from our model, that the extent of permutation is a direct function of the length of terminal repetition.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jss.400020216
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