Different Phenotypes in Vivo Are Associated With ATPase Motif Mutations in Schizosaccharomyces pombe Minichromosome Maintenance Proteins

Corresponding author: Susan L. Forsburg, The Salk Institute, 10010 N. Torrey Pines Rd., La Jolla, CA., forsburg{at}salk.edu (E-mail)

Communicating editor: P. RUSSELL

The six conserved MCM proteins are essential for normal DNA replication. They share a central core of homology that contains sequences related to DNA-dependent and AAA⁺ ATPases. It has been suggested that the MCMs form a replicative helicase because a hexameric subcomplex formed by MCM4, -6, and -7 proteins has in vitro DNA helicase activity. To test whether ATPase and helicase activities are required for MCM protein function in vivo, we mutated conserved residues in the Walker A and Walker B motifs of MCM4, -6, and -7 and determined that equivalent mutations in these three proteins have different in vivo effects in fission yeast. Some mutations reported to abolish the in vitro helicase activity of the mouse MCM4/6/7 subcomplex do not affect the in vivo function of fission yeast MCM complex. Mutations of consensus CDK sites in Mcm4p and Mcm7p also have no phenotypic consequences. Co-immunoprecipitation analyses and in situ chromatin-binding experiments were used to study the ability of the mutant Mcm4ps to associate with the other MCMs, localize to the nucleus, and bind to chromatin. We conclude that the role of ATP binding and hydrolysis is different for different MCM subunits.

This article has been cited by other articles:

				M. L. Bochman, S. P. Bell, and A. Schwacha Subunit Organization of Mcm2-7 and the Unequal Role of Active Sites in ATP Hydrolysis and Viability Mol. Cell. Biol., October 1, 2008; 28(19): 5865 - 5873. [Abstract] [Full Text] [PDF]

				E. B. Gomez, R. L. Nugent, S. Laria, and S. L. Forsburg Schizosaccharomyces pombe Histone Acetyltransferase Mst1 (KAT5) Is an Essential Protein Required for Damage Response and Chromosome Segregation Genetics, June 1, 2008; 179(2): 757 - 771. [Abstract] [Full Text] [PDF]

				M. L. Bochman and A. Schwacha Differences in the Single-stranded DNA Binding Activities of MCM2-7 and MCM467: MCM2 AND MCM5 DEFINE A SLOW ATP-DEPENDENT STEP J. Biol. Chem., November 16, 2007; 282(46): 33795 - 33804. [Abstract] [Full Text] [PDF]

				H. Masai, C. Taniyama, K. Ogino, E. Matsui, N. Kakusho, S. Matsumoto, J.-M. Kim, A. Ishii, T. Tanaka, T. Kobayashi, et al. Phosphorylation of MCM4 by Cdc7 Kinase Facilitates Its Interaction with Cdc45 on the Chromatin J. Biol. Chem., December 22, 2006; 281(51): 39249 - 39261. [Abstract] [Full Text] [PDF]

				E. B. Gomez, J. M. Espinosa, and S. L. Forsburg Schizosaccharomyces pombe mst2+ Encodes a MYST Family Histone Acetyltransferase That Negatively Regulates Telomere Silencing Mol. Cell. Biol., October 15, 2005; 25(20): 8887 - 8903. [Abstract] [Full Text] [PDF]

				L. L. Freeman-Cook, E. B. Gomez, E. J. Spedale, J. Marlett, S. L. Forsburg, L. Pillus, and P. Laurenson Conserved Locus-Specific Silencing Functions of Schizosaccharomyces pombe sir2+ Genetics, March 1, 2005; 169(3): 1243 - 1260. [Abstract] [Full Text] [PDF]

				E. B. Gomez, V. T. Angeles, and S. L. Forsburg A Screen for Schizosaccharomyces pombe Mutants Defective in Rereplication Identifies New Alleles of rad4+, cut9+ and psf2+ Genetics, January 1, 2005; 169(1): 77 - 89. [Abstract] [Full Text] [PDF]

				S. L. Forsburg Eukaryotic MCM Proteins: Beyond Replication Initiation Microbiol. Mol. Biol. Rev., March 1, 2004; 68(1): 109 - 131. [Abstract] [Full Text] [PDF]

				D. L. Kaplan, M. J. Davey, and M. O'Donnell Mcm4,6,7 Uses a "Pump in Ring" Mechanism to Unwind DNA by Steric Exclusion and Actively Translocate along a Duplex J. Biol. Chem., December 5, 2003; 278(49): 49171 - 49182. [Abstract] [Full Text] [PDF]

				D. Schaarschmidt, E.-M. Ladenburger, C. Keller, and R. Knippers Human Mcm proteins at a replication origin during the G1 to S phase transition Nucleic Acids Res., October 1, 2002; 30(19): 4176 - 4185. [Abstract] [Full Text] [PDF]