DNA packaging and cutting by phage terminases: control in phage T4 by a synaptic mechanism.
Phage DNA packaging occurs by DNA translocation into a prohead. Terminases are enzymes which initiate DNA packaging by cutting the DNA concatemer, and they are closely fitted structurally to the portal vertex of the prohead to form a 'packasome'. Analysis among a number of phages supports an active role of the terminases in coupling ATP hydrolysis to DNA translocation through the portal. In phage T4 the small terminase subunit promotes a sequence-specific terminase gene amplification within the chromosome. This link between recombination and packaging suggests a DNA synapsis mechanism by the terminase to control packaging initiation, formally homologous to eukaryotic chromosome segregation.
Black
L W
LW
Department of Biological Chemistry, University of Maryland Medical School, Baltimore 21201, USA.
D017122:Bacteriophage T4 / Q000201:enzymology / Q000502:physiology*; D004279:DNA, Viral / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D019065:Virus Assembly / Q000502:physiology*
D004279:DNA, Viral; D004706:Endodeoxyribonucleases; C030894:terminase