Coupling of DNA binding and helicase activity is mediated by a conserved loop in the MCM protein.
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 beta7 and beta8 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.
Sakakibara
Nozomi
N
University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology, 9600 Gudelsky Drive, Rockville, MD 20850, USA.
Kasiviswanathan
Rajesh
R
Melamud
Eugene
E
Han
Mimi
M
Schwarz
Frederick P
FP
Kelman
Zvi
Z
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017013:Methanobacteriaceae / Q000201:enzymology*; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary
D019843:Archaeal Proteins; D004268:DNA-Binding Proteins; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases