 |
PDBsum entry 1ltl
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
The structure and function of mcm from archaeal m. Thermoautotrophicum.
|
|
|
Authors
|
|
R.J.Fletcher,
B.E.Bishop,
R.P.Leon,
R.A.Sclafani,
C.M.Ogata,
X.S.Chen.
|
|
|
Ref.
|
|
Nat Struct Biol, 2003,
10,
160-167.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Eukaryotic chromosomal DNA is licensed for replication precisely once in each
cell cycle. The mini-chromosome maintenance (MCM) complex plays a role in this
replication licensing. We have determined the structure of a fragment of MCM
from Methanobacterium thermoautotrophicum (mtMCM), a model system for eukaryotic
MCM. The structure reveals a novel dodecameric architecture with a remarkably
long central channel. The channel surface has an unusually high positive charge
and binds DNA. We also show that the structure of the N-terminal fragment is
conserved for all MCMs proteins despite highly divergent sequences, suggesting a
common architecture for a similar task: gripping/remodeling DNA and regulating
MCM activity. An mtMCM mutant protein equivalent to a yeast MCM5 (CDC46) protein
with the bob1 mutation at its N terminus has only subtle structural changes,
suggesting a Cdc7-bypass mechanism by Bob1 in yeast. Yeast bypass experiments
using MCM5 mutant proteins support the hypothesis for the bypass mechanism.
|
|
|
|
|
|
|
|
Figure 1.
Figure 1. Overall structure of double-hexamer of N-mtMCM. a,
Side view of the double-hexamer structure. Each monomer is
represented by a discrete color. The  -helices
are represented by cylinders; and  -strands,
by arrows. The 12 Zn atoms (magenta) are located in the middle
of the double hexamer, mediating hexamer -hexamer interactions.
The figure was generated with MolScript44. b, A surface
representation of the double hexamer, showing a dumbbell-like
shape. The figure was generated with GRASP45. c, The packing of
the double hexamers in the crystal, viewed along the two-fold
and normal to the three-fold crystallographic axis. Three
consecutive double hexamers (in blue, magenta and green) are
stacked end-to-end against each other.
|
|
Figure 6.
Figure 6. Yeast bypass results of mutations of MCM5 at Pro83
supporting the domain-push hypothesis for bob1 bypass mechanism.
a, Cells of S. cerevisiae strain 302 with cdc7ts containing
either wild type or mutant alleles of MCM5 were diluted serially
from 10^0 to 10^-4 (right to left), placed on YPD plates (see
Methods) and then incubated at either permissive (22 °C) or
non-permissive (36 °C) temperature for 2 d. b, Summary of
results. Yes indicates growth and No means no growth at the
indicated temperature. *Bypass occurs when cdc7ts cells grow at
36 °C.
|
|
|
|
|
|
The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol
(2003,
10,
160-167)
copyright 2003.
|
|
|
|
|
|
|
