Black L W
Department of Biological Chemistry, University of Maryland Medical School, Baltimore 21201, USA.
Bioessays. 1995 Dec;17(12):1025-30. doi: 10.1002/bies.950171206.
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.
噬菌体DNA包装是通过将DNA转运到原头部来实现的。末端酶是通过切割DNA多联体来启动DNA包装的酶，它们在结构上与原头部的门户顶点紧密契合，形成一个“包装体”。对多种噬菌体的分析支持末端酶在将ATP水解与通过门户的DNA转运偶联中发挥积极作用。在噬菌体T4中，小末端酶亚基促进染色体中序列特异性的末端酶基因扩增。重组与包装之间的这种联系表明，末端酶存在一种DNA联会机制来控制包装起始，这在形式上与真核染色体分离同源。
