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Title
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The crystal structure of p13suc1, a p34cdc2-interacting cell cycle control protein.
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Authors
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J.A.Endicott,
M.E.Noble,
E.F.Garman,
N.Brown,
B.Rasmussen,
P.Nurse,
L.N.Johnson.
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Ref.
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Embo J, 1995,
14,
1004-1014.
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PubMed id
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Abstract
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p13suc1 binds to p34cdc2 kinase and is essential for cell cycle progression in
eukaryotic cells. The crystal structure of S.pombe p13suc1 has been solved to
2.7 A resolution using data collected at the ESRF source, Grenoble, from both
native crystals and crystals of a seleno-methionine derivative. The starting
point for structure solution was the determination of the six selenium sites by
direct methods. The structure is dominated by a four-stranded beta-sheet, with
four further alpha-helical regions. p13suc1 crystallizes as a dimer in the
asymmetric unit stabilized by the binding of two zinc ions. A third zinc site
stabilizes the higher-order crystal packing. The sites are consistent with a
requirement for zinc during crystal growth. A likely site for p13suc1-protein
interaction is immediately evident on one face of the p13suc1 surface. This
region comprises a group of conserved, exposed aromatic and hydrophobic residues
below a flexible negatively charged loop. A conserved positively charged area
would also present a notable surface feature in the monomer, but is buried at
the dimer interface. p13suc1 is larger than its recently solved human homologue
p9CKS2, with the extra polypeptide forming a helical N-terminal extension and a
surface loop between alpha-helices 3 and 4. Notably, p13suc1 does not show the
unusual beta-strand exchange that creates an intimate p9CKS2 dimer. p13suc1
cannot oligomerize to form a stable hexamer as has been proposed for p9CKS2.
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