HYDROLYSIS OF ATP DEPENDENT ON HOMOLOGOUS DOUBLE-STRANDED DNA AND SINGLE-STRANDED FRAGMENTS PROMOTED BY RECA PROTEIN OF ESCHERICHIA-COLI
HYDROLYSIS OF ATP DEPENDENT ON HOMOLOGOUS DOUBLE-STRANDED DNA AND SINGLE-STRANDED FRAGMENTS PROMOTED BY RECA PROTEIN OF ESCHERICHIA-COLI
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DOI：
10.1093/oxfordjournals.jbchem.a133869
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发表时间：
1982-01-01
影响因子：
2.7
通讯作者：
ANDO, T
中科院分区：
文献类型：
--
作者：
OHTANI, T;SHIBATA, T;ANDO, T
RecA蛋白在大肠杆菌的一般遗传重组中是必需的。杆菌在ATP存在下，化学计量量的recA蛋白从超螺旋闭环DNA（I型DNA）和同源单链片段形成D环，随后解离D环。在适当的条件下，recA蛋白对ATP的水解依赖于双链DNA和同源单链片段的存在（同源依赖性水解）。在I型DNA的存在下，recA蛋白对ATP的大部分同源依赖性水解与D-环的解离而不是D-环的形成有关。在存在缺口环状DNA（II型DNA）的情况下，RecA蛋白还促进ATP的同源依赖性水解，但与I型DNA的情况不同，这种水解与检测到的成熟D环数量的增加有关。D环测定。当双链DNA是超螺旋时，即使在所有的D-环解离之后，ATP的同源依赖性水解仍以相同的速率继续。这与早期的观察结果相关，即在D-环形成和解离的过程中，I型DNA被转化为无活性底物，而对DNA没有任何明显的损伤，这可能是通过与recA蛋白形成复合物。上述所有观察结果都可以用一个模型来解释，其中一个共同的机制导致D-环从I型DNA上解离，I型DNA失活，以及II型DNA中D-环的生长。该机制可能涉及recA蛋白从新生D环的位点与双链体DNA的合作结合，导致双链体DNA的单向解旋。
RecA protein is essential to general genetic recombination in E. coli. In the presence of ATP, a stoichiometric amount of recA protein forms D-loops from superhelical closed-circular DNA (form I DNA) and homologous single-stranded fragments, and subsequently dissociates the D-loops. Under appropriate conditions, the hydrolysis of ATP by recA protein depends on the presence of both double-stranded DNA and homologous single-stranded fragments (homology-dependent hydrolysis). In the presence of form I DNA, most of the homology-dependent hydrolysis of ATP by recA protein is related to the dissociation of D-loops rather than the formation of D-loops. RecA protein also promoted the homology-dependent hydrolysis of ATP in the presence of nicked-circular DNA (form II DNA), but unlike the case of form I DNA, this hydrolysis was associated with an increase in the amount of mature D-loops that were detected by the D-loop assay. When double-stranded DNA was superhelical, the homology-dependent hydrolysis of ATP continued at the same rate even after all the D-loops were dissociated. This correlates with the earlier observation that in the process of formation and dissociation of D-loops, form I DNA was converted to an inactive substrate without any apparent damage to the DNA, probably by the formation of a complex with recA protein. All of the observations described above can be explained by a model in which a common mechanism causes dissociation of D-loops from form I DNA, inactivation of form I DNA, and growth of D-loops in form II DNA. The mechanism might involve cooperative binding of recA protein to the duplex DNA from the site of the nascent D-loop, resulting in unidirectional unwinding of the duplex DNA.