Nucleic Acids Research Advance Access published online on January 9, 2008
Nucleic Acids Research, doi:10.1093/nar/gkm1160
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Nucleic Acid Enzymes |
Coupling of DNA binding and helicase activity is mediated by a conserved loop in the MCM protein
1University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology, 9600 Gudelsky Drive, Rockville, MD 20850 and 2National Institute of Standards and Technology, 9600 Gudelsky Drive, Rockville, MD 20850.
*To whom correspondence should be addressed. Tel: (240) 314–6294; Fax: (240) 314-6255; Email: kelman{at}umbi.umd.edu
Received November 13, 2007. Revised December 11, 2007. Accepted December 14, 2007.
Minichromosome maintenance (MCM) helicases are the presumptive replicative helicases, thought to separate the two strands of chromosomal DNA during replication. In archaea, the catalytic activity resides within the C-terminal region of the MCM protein. In Methanothermobacter thermautotrophicus the N-terminal portion of the protein was shown to be involved in protein multimerization and binding to single and double stranded DNA. MCM homologues from many archaeal species have highly conserved predicted amino acid similarity in a loop located between β7 and β8 in the N-terminal part of the molecule. This high degree of conservation suggests a functional role for the loop. Mutational analysis and biochemical characterization of the conserved residues suggest that the loop participates in communication between the N-terminal portion of the helicase and the C-terminal catalytic domain. Since similar residues are also conserved in the eukaryotic MCM proteins, the data presented here suggest a similar coupling between the N-terminal and catalytic domain of the eukaryotic enzyme.
Present addresses: Rajesh Kasiviswanathan, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, 111 TW Alexander Dr., Research Triangle Park, NC 27709.
Eugene Melamud Lewis-Sigler Institute for Integrative Genomics, Princeton University, 241 Carl Icahn Laboratory, Washington Road, Princeton, NJ 08544.