Isolation and characterization of a portal protein-DNA complex from dsDNA bacteriophage.
A portal protein-DNA complex was isolated from bacteriophage disrupted in 70% acetic acid. This treatment dissociated most of the phage structural proteins, while the portal protein ring remained attached to the highly condensed naked DNA. In the absence of a headful of DNA, the portal ring was not protected. Purification of the portal ring-DNA complex by density gradient centrifugation showed that a dsDNA fragment of about 40 bp was protected from DNase digestion by this association, suggesting it was internalized within the 140 A long, 20-40 A in diameter T4 apical channel of the ring dodecamer. A portal ring-DNA complex could be isolated from a number of phages (T4, T7, Phi29), and the end(s) of phage T7 DNA was (were) found to be preferentially associated with the ring complex.
Zachary
A
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Department of Biological Chemistry, University of Maryland Medical School, Baltimore.
Black
L W
LW
D000085:Acetates; D019342:Acetic Acid; D002213:Capsid / Q000302:isolation & purification* / Q000648:ultrastructure; D004279:DNA, Viral / Q000302:isolation & purification*; D008854:Microscopy, Electron; D011487:Protein Conformation; D013604:T-Phages / Q000737:chemistry* / Q000648:ultrastructure
D000085:Acetates; D004279:DNA, Viral; D019342:Acetic Acid