West S C, Countryman J K, Howard-Flanders P
J Biol Chem. 1983 Apr 10;258(7):4648-54.
The product of the cloned recA+ gene of Proteus mirabilis substitutes for a defective recA protein in Escherichia coli recA- mutants and restores recombination, repair, and prophage induction functions to near normal levels (Eitner, G., Adler, B., Lanzov, V. A., and Hofemeister, J. (1982) Mol. Gen. Genet. 185, 481-486). In this paper, we report the purification to near homogeneity of the P. mirabilis recA protein (recApm). The polypeptide has a molecular weight similar to that of E. coli recA protein (recAec) and shows partial identity with recAec when reacted against antibodies specific for the E. coli recA protein. recApm catalyzes the hydrolysis of ATP in the presence of single-stranded but not double-stranded DNA. We have compared the recombination-like activities of recApm with those of recAec and found them to be similar. In the presence of ATP and Mg2+, stoichiometric amounts of recApm promote the complete reciprocal exchange of strands between gapped circular and linear duplex DNA molecules. The enzyme also efficiently promotes the formation of D-loops from circular duplex DNA and homologous single-stranded fragments. However, although recApm and recAec share the above physical and functional similarities, they differ in their ability to interact with the E. coli single strand binding protein to catalyze the transfer of one DNA strand from a linear duplex to a single-stranded circle.
奇异变形杆菌克隆的recA⁺基因产物可替代大肠杆菌recA⁻突变体中缺陷的recA蛋白，并将重组、修复和原噬菌体诱导功能恢复到接近正常水平（艾特纳，G.，阿德勒，B.，兰佐夫，V. A.，和霍费迈斯特，J.（1982年）《分子与普通遗传学》185卷，481 - 486页）。在本文中，我们报告了奇异变形杆菌recA蛋白（recApm）的纯化，纯化后的蛋白接近均一。该多肽的分子量与大肠杆菌recA蛋白（recAec）相似，当与针对大肠杆菌recA蛋白的特异性抗体反应时，与recAec显示出部分同源性。recApm在单链而非双链DNA存在的情况下催化ATP水解。我们比较了recApm与recAec的类重组活性，发现它们相似。在ATP和Mg²⁺存在的情况下，化学计量的recApm促进有缺口的环状和线性双链DNA分子之间链的完全相互交换。该酶还能有效地促进环状双链DNA与同源单链片段形成D环。然而，尽管recApm和recAec具有上述物理和功能上的相似性，但它们在与大肠杆菌单链结合蛋白相互作用以催化一条DNA链从线性双链转移到单链环的能力方面存在差异。
