A Biochemically Active MCM-like Helicase in Bacillus Cereus
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CitationSamuels, Martin, Gaurav Gulati, Jae-Ho Shin, Rejoice Opara, Elizabeth McSweeney, Matt Sekedat, Stephen Long, Zvi Kelman, and David Jeruzalmi. 2009. A Biochemically active MCM-like helicase in Bacillus cereus. Nucleic Acids Research 37(13): 4441-52.
AbstractThe mini-chromosome maintenance (MCM) proteins serve as the replicative helicases in archaea and eukaryotes. Interestingly, an MCM homolog was identified, by BLAST analysis, within a phage integrated in the bacterium Bacillus cereus (Bc). BcMCM is only related to the AAA region of MCM-helicases; the typical amino-terminus is missing and is replaced by a segment with weak homology to primases. We show that BcMCM displays 3'-->5' helicase and ssDNA-stimulated ATPase activity, properties that arise from its conserved AAA domain. Isolated BcMCM is a monomer in solution but likely forms the functional oligomer in vivo. We found that the BcMCM amino-terminus can bind ssDNA and harbors a zinc atom, both hallmarks of the typical MCM amino-terminus. No BcMCM-catalyzed primase activity could be detected. We propose that the divergent amino-terminus of BcMCM is a paralog of the corresponding region of MCM-helicases. A divergent amino terminus makes BcMCM a useful model for typical MCM-helicases since it accomplishes the same function using an apparently unrelated structure.
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