DNA-STRAND EXCHANGE PROMOTED BY RECA PROTEIN IN THE ABSENCE OF ATP - IMPLICATIONS FOR THE MECHANISM OF ENERGY TRANSDUCTION IN PROTEIN-PROMOTED NUCLEIC-ACID TRANSACTIONS
DNA-STRAND EXCHANGE PROMOTED BY RECA PROTEIN IN THE ABSENCE OF ATP - IMPLICATIONS FOR THE MECHANISM OF ENERGY TRANSDUCTION IN PROTEIN-PROMOTED NUCLEIC-ACID TRANSACTIONS
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DOI：
10.1073/pnas.92.8.3478
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发表时间：
1995-04-11
影响因子：
11.1
通讯作者：
KRUPP, RA
中科院分区：
文献类型：
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作者：
KOWALCZYKOWSKI, SC;KRUPP, RA
由大肠杆菌RecA蛋白促进的DNA链交换通常需要ATP的存在，并伴随着ATP水解，从而意味着需要ATP水解。以前，ATP水解被证明是不需要的，在这里，我们进一步证明，核苷三磷酸辅因子是不需要的DNA链交换。由ADP和氟化铝的非共价复合物ADP·AlF 4-组成的无偿变构效应物既可以诱导RecA蛋白的高亲和力DNA结合状态，又可以支持高达800-900 bp的DNA的同源配对和交换。这些结果表明，RecA蛋白促进的DNA链交换需要RecA蛋白的功能活性，高亲和力的DNA结合状态的诱导，并且不需要用于DNA链交换的高能核苷酸辅因子。因此，激活DNA底物进行DNA链交换所需的自由能不是来自ATP水解。相反，所需的自由能来自配体结合，并通过RecA蛋白-DNA复合物的相关配体诱导的结构转变转导到DNA; ATP水解简单地破坏效应配体。这一概念对蛋白质的能量转导机制具有普遍适用性。
DNA-strand exchange promoted by Escherichia coli RecA protein normally requires the presence of ATP and is accompanied by ATP hydrolysis, thereby implying a need for ATP hydrolysis. Previously, ATP hydrolysis was shown not to be required; here we demonstrate furthermore that a nucleoside triphosphate cofactor is not required for DNA-strand exchange. A gratuitous allosteric effector consisting of the noncovalent complex of ADP and aluminum fluoride, ADP.AlF4-, can both induce the high-affinity DNA-binding state of RecA protein and support the homologous pairing and exchange of up to 800-900 bp of DNA. These results demonstrate that induction of the functionally active, high-affinity DNA-binding state of RecA protein is needed for RecA protein-promoted DNA-strand exchange and that there is no requirement for a high-energy nucleotide cofactor for the exchange of DNA strands. Consequently, the free energy needed to activate the DNA substrates for DNA-strand exchange is not derived from ATP hydrolysis. Instead, the needed free energy is derived from ligand binding and is transduced to the DNA via the associated ligand-induced structural transitions of the RecA protein-DNA complex; ATP hydrolysis simply destroys the effector ligand. This concept has general applicability to the mechanism of energy transduction by proteins.