hMutSα forms an ATP-dependent complex with hMutLα and hMutLβ on DNA |
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Authors: | Guido Plotz Jochen Raedle Angela Brieger Jrg Trojan and Stefan Zeuzem |
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Institution: | Guido Plotz, Jochen Raedle, Angela Brieger, Jörg Trojan, and Stefan Zeuzem |
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Abstract: | The DNA binding properties of hMutSα and hMutLα and complex formation of hMutSα with hMutLα and hMutLβ were investigated using binding experiments on magnetic bead-coupled DNA substrates with nuclear extracts as well as purified proteins. hMutSα binding to homoduplex DNA was disrupted by lower NaCl concentrations than hMutSα binding to a mismatch. ATP markedly reduced the salt resistance of hMutSα binding but hMutSα still retained affinity for heteroduplexes. hMutSα formed a complex with hMutLα and hMutLβ on DNA in the presence of ATP. This complex only formed on 81mer and not 32mer DNA substrates. Complex formation was enhanced by a mismatch in the DNA substrate, and hMutLα and hMutLβ were shown to enter the complex at different ATP concentrations. Purified hMutLα showed an intrinsic affinity for DNA, with a preference for single-stranded over double-stranded DNA. |
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