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Title
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Substrate specificity and assembly of the catalytic center derived from two structures of ligated uridylate kinase.
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Authors
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H.J.Müller-Dieckmann,
G.E.Schulz.
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Ref.
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J Mol Biol, 1995,
246,
522-530.
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PubMed id
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Abstract
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Two crystal structures of ligated uridylate kinase from Saccharomyces cerevisiae
were determined by X-ray analyses. The ligands were ADP and AMP.
Cocrystallization with ATP yielded crystals with ADP at the ATP site and a
mixture of AMP and ADP at the NMP site. Cocrystallization with ADP gave rise to
a distinct crystal type with ADP at the ATP site, but only AMP at the NMP site.
In both cases, the substrates are kept in place by favorable crystal contacts.
The structures have been refined to R-factors of 17.8% and 19.6% at resolutions
of 2.1 A and 1.9 A, respectively. A comparison with the related cytosolic
adenylate kinase from pig disclosed large induced-fit movements on substrate
binding and the disassembly of the catalytic center in the absence of
substrates. The relatively high side-activity of uridylate kinase for AMP is
explained by the finding that the binding pocket is sized for an AMP, but
constructed to bind UMP together with a water molecule.
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