The bacteriophage phi 29 packaging proteins supercoil the DNA ends
The bacteriophage phi 29 packaging proteins supercoil the DNA ends
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DOI：
10.1006/jmbi.1996.0843
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发表时间：
1997-03-14
影响因子：
5.6
通讯作者：
Anderson, D
中科院分区：
文献类型：
--
作者：
Grimes, S;Anderson, D
噬菌体phi 29 DNA与共价结合的末端蛋白（DNA-gp 3）和它的左，右端限制性片段（L和R-DNA-gp 3）在蔗糖密度梯度比蛋白酶K处理的同行沉降更快，更快的沉降是gp 3和Mg 2+依赖。加入gp 16（phi 29 DNA包装ATP酶）进一步增加了完整DNA-gp 3和L和R-DNA-gp 3片段的沉降速率。因此，含有gp 3的DNA比不含gp 3的DNA更紧凑，并且gp 16进一步浓缩DNA-gp 3形式。[S-35] gp 16与快速沉淀的DNA-gp 3片段共沉淀，推测的L-DNA-gp 3-gp 16复合物在确定的体外系统中被优先包装到前体中。通过电子显微镜观察到的DNA-gp 3和L和R-DNA-gp 3的larariats合理的沉降结果，和larariats与多个环或线圈增加了10倍，在制备L-DNA-gp 3-gp 16复合物。的快速沉降和DNA-gp 3-gp 16复合物的结构是一致的超螺旋的liscoeling循环，和治疗与拓扑异构酶I转移快速沉降复合物向解螺旋liscoeling位置在蔗糖密度梯度。DNA-gp 3具有成熟途径，其中包装蛋白gp 3和gp 16超螺旋DNA末端，可能是与prohead有效相互作用的先决条件。(C)出版社：Academic Press Limited。
Bacteriophage phi 29 DNA with covalently bound terminal protein (DNA-gp3) and its left and right-end restriction fragments (L and R-DNA-gp3) sedimented faster in sucrose density gradients than their proteinase K-treated counterparts, and the faster sedimentation was both gp3 and Mg2+-dependent. Addition of gp16, the phi 29 DNA packaging ATPase, further increased the sedimentation rates of both intact DNA-gp3 and L and R-DNA-gp3 fragments. Thus, DNAs with gp3 were more compact than gp3-free DNA, and gp16 further condensed the DNA-gp3 forms. [S-35]gp16 cosedimented with the fast-sedimenting DNA-gp3 fragments, and the putative L-DNA-gp3-gp16 complexes were packaged preferentially into proheads in the defined in vitro system. Lariats of DNA-gp3 and L and R-DNA-gp3 observed by electron microscopy rationalized the sedimentation results, and lariats with multiple loops or coils increased tenfold in a preparation of L-DNA-gp3-gp16 complexes. The rapid sedimentation and the structure of the DNA-gp3-gp16 complexes were consistent with supercoiling of lariat loops, and treatment with topoisomerase I shifted fast-sedimenting complexes toward the uncoiled lariat position in sucrose density gradients. DNA-gp3 has a maturation pathway in which the packaging proteins gp3 and gp16 supercoil the DNA ends, probably as a prerequisite for efficient interaction with the prohead. (C) 1997 Academic Press Limited.