Topologies of Complexes Containing O6-Alkylguanine-DNA Alkyltransferase and DNA

Claire A. Adams, Manana Melikishvili, David W. Rodgers, Joseph J. Rasimas, Anthony E. Pegg, Michael G. Fried

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

The mutagenic and cytotoxic effects of many alkylating agents are reduced by O6-alkylguanine-DNA alkyltransferase (AGT). In humans, this protein not only protects the integrity of the genome, but also contributes to the resistance of tumors to DNA-alkylating chemotherapeutic agents. Here we describe and test models for cooperative multiprotein complexes of AGT with single-stranded and duplex DNAs that are based on in vitro binding data and the crystal structure of a 1:1 AGT-DNA complex. These models predict that cooperative assemblies contain a three-start helical array of proteins with dominant protein-protein interactions between the amino-terminal face of protein n and the carboxy-terminal face of protein n + 3, and they predict that binding duplex DNA does not require large changes in B-form DNA geometry. Experimental tests using protein cross-linking analyzed by mass spectrometry, electrophoretic and analytical ultracentrifugation binding assays, and topological analyses with closed circular DNA show that the properties of multiprotein AGT-DNA complexes are consistent with these predictions.

Original languageEnglish (US)
Pages (from-to)248-263
Number of pages16
JournalJournal of Molecular Biology
Volume389
Issue number2
DOIs
StatePublished - Jun 5 2009

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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