ADP binding induces long-distance structural changes in the beta polypeptide of the chloroplast ATP synthase.
ADP binding induces long-distance structural changes in the beta polypeptide of the chloroplast ATP synthase.
复制标题
ADP 结合诱导叶绿体 ATP 合酶的 β 多肽发生长距离结构变化。
DOI：
10.1021/bi00018a013
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
Richter,ML
中科院分区：
文献类型：
--
作者：
Mills,DA;Seibold,SA;Squier,TC;Richter,ML
Revised Manuscript Received February 24, 1995® abstract: Binding of ADP to the ß polypeptide isolated from the catalytic Fi portion (CFO of the chloroplast ATP synthasecaused an increase of 10—20% in the steady state fluorescence intensity of fluorescent maleimides attachedto the cysteine residue at position 63. Fluorescence lifetime distributions indicated that the ß polypeptide switched between two conformational states depending on the presence or absence of bound ADP. The fluorescence enhancement induced by ADP binding allowed a direct calculation of the dissociation constant for ADP of 0.7 µ. ATP did not cause a fluorescence enhancement but competed with ADP for binding to the same site. An apparent dissociation constant of 2 µ was obtained for ATP binding. Fluorescence resonance energy transfer experiments indicated that Cys63 is 42 Á away from the nucleotidebinding site on the ß polypeptide, confirming a previous measurement [(Colvert, KK, Mills, DA, Richter, ML (1992) Biochemistry 31, 3930—3935], Frequency domain fluorescence anisotropy measurements indicated that the ß polypeptide has an irregular, elongated shape which is in good agreement with the conformation found in the crystal structure of the beef heart mitochondrial Fi enzyme [Abrahams, J. P., Leslie, A. G. W., flutter, R., & Walker, J. E.(1994) Nature 370, 621—628], The rotational correlation timedid not change significantly upon ADP binding, indicating that ADP did not induce a large change in the overall shape of the ß polypeptide. The results show that the nucleotidebinding domain and the N-terminal domain of the ß polypeptide communicate with each other over a significant distance via conformational changes. This supports several other recent findings which have indicated thatthe N-terminal region of the ß polypeptide forms a site of contact with the a polypeptide and that this contact site is important for cooperativeexchange of information between nucleotide binding sites during catalysis by CFi.
