The zinc finger domain of the archaeal minichromosome maintenance protein is required for helicase activity.
The minichromosome maintenance (MCM) proteins, a family of six conserved polypeptides found in all eukaryotes, are essential for DNA replication. The archaeon Methanobacterium thermoautotrophicum Delta H contains a single homologue of MCM with biochemical properties similar to those of the eukaryotic enzyme. The amino acid sequence of the archaeal protein contains a putative zinc-binding domain of the CX(2)CX(n)CX(2)C (C(4)) type. In this study, the roles of the zinc finger domain in MCM function were examined using recombinant wild-type and mutant proteins expressed and purified from Escherichia coli. The protein with a mutation in the zinc motif forms a dodecameric complex similar to the wild-type enzyme. The mutant enzyme, however, is impaired in DNA-dependent ATPase activity and single-stranded DNA binding, and it does not possess helicase activity. These results illustrate the importance of the zinc-binding domain for archaeal MCM function and suggest a role for zinc binding in the eukaryotic MCM complex as well, since four out of the six eukaryotic MCM proteins contain a similar zinc-binding motif.
Poplawski
A
A
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA.
Grabowski
B
B
Long
S E
SE
Kelman
Z
Z
D000595:Amino Acid Sequence; D000818:Animals; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017014:Methanobacterium / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D016335:Zinc Fingers
D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D004247:DNA; D004265:DNA Helicases; C403162:MCM protein, Methanobacterium thermoautotrophicum