On the solution structure of the T4 sliding clamp (gp45)
On the solution structure of the T4 sliding clamp (gp45)
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DOI：
10.1021/bi048349c
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发表时间：
2004-10-12
期刊：
影响因子：
2.9
通讯作者：
Benkovic, SJ
中科院分区：
文献类型：
--
作者：
Millar, D;Trakselis, MA;Benkovic, SJ
用荧光共振能量转移(FRET)对标记在其三个亚基界面上的三聚体噬菌体T4夹蛋白的时间分辨荧光光谱检测表明，该夹子在溶液中仅以一种状态存在，具有一个开放的界面和两个封闭的界面。这与在X射线晶体结构中观察到的情况相反。TrFRET距离的布居分布为双峰分布，67%为17埃，33%为42A，从而得出gp45在溶液中以不对称的开态存在的结论。在钳位加载器和ATP存在的情况下，FRET对分离的进一步增加可归因于开放界面的进一步开放或封闭界面的开放。讨论了该途径对复制体重塑的影响。
Examination by time-resolved fluorescence spectroscopy of the trimeric bacteriophage T4 clamp protein labeled across its three subunit interfaces with a fluorescence resonance energy transfer (FRET) pair indicates that the clamp exists in just one state in solution, with one open and two closed interfaces. This is in contrast to what is observed in the X-ray crystal structure. The population distribution of the trFRET distance is bimodal, giving 67% as 17 Angstrom and 33% as 42 A. This leads to the conclusion that gp45 exists in an asymmetric open state in solution. The further increase in the separation of the FRET pair in the presence of the clamp loader and ATP may be ascribed to either further opening of the open interface or the opening of a closed interface. The ramifications for replisome remodeling by this pathway are discussed.