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The Methanobacterium thermoautotrophicum MCM protein can form heptameric rings
Author(s) -
Yu Xiong,
VanLoock Margaret S,
Poplawski Andrzej,
Kelman Zvi,
Xiang Tao,
Tye Bik K,
Egelman Edward H
Publication year - 2002
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1093/embo-reports/kvf160
Subject(s) - biology , methanobacterium , bacteria , chemistry , genetics , archaea
Mini‐chromosome maintenance (MCM) proteins form a conserved family found in all eukaryotes and are essential for DNA replication. They exist as heteromultimeric complexes containing as many as six different proteins. These complexes are believed to be the replicative helicases, functioning as hexameric rings at replication forks. In most archaea a single MCM protein exists. The protein from Methanobacterium thermoautotrophicum (mtMCM) has been reported to assemble into a large complex consistent with a dodecamer. We show that mtMCM can assemble into a heptameric ring. This ring contains a C‐terminal helicase domain that can be fit with crystal structures of ring helicases and an N‐terminal domain of unknown function. While the structure of the ring is very similar to that of hexameric replicative helicases such as bacteriophage T7 gp4, our results show that such ring structures may not be constrained to have only six subunits.