A biochemically active MCM-like helicase in Bacillus cereus

作者：Samuels Martin; Gulati Gaurav; Shin Jae Ho; Opara Rejoice; McSweeney Elizabeth; Sekedat Matt; Long Stephen; Kelman Zvi; Jeruzalmi David^*

来源：Nucleic Acids Research, 2009, 37(13): 4441-4452.

DOI：10.1093/nar/gkp376

The 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.

• 出版日期2009-7