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Title
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Structure of the complex of yeast adenylate kinase with the inhibitor P1,P5-di(adenosine-5'-)pentaphosphate at 2.6 A resolution.
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Authors
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U.Egner,
A.G.Tomasselli,
G.E.Schulz.
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Ref.
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J Mol Biol, 1987,
195,
649-658.
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PubMed id
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Abstract
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Adenylate kinase from yeast cytosol was crystallized as a 1:1 complex with the
inhibitor P1,P5-di(adenosine-5'-)pentaphosphate. The crystalline structure was
solved by multiple isomorphous replacement at a resolution of 3 A (1 A = 0.1 nm)
and subsequent structural refinement at 2.6 A resolution. The yeast enzyme
belongs to the group of large variants among the adenylate kinases, whereas the
structurally known porcine cytosolic enzyme is a small variant. A comparison
showed that the additional 31-residue segment of the large variants covers the
active center. This had not been expected, because small and large variants show
similar enzyme kinetics. Apart from this insertion, the chain folds of both
adenylate kinases are the same. The yeast enzyme with bound inhibitor, however,
assumes a much more closed form. In relation to the porcine enzyme without
substrate, a segment of 28 residues containing two helices is rotated by about
30 degrees, closing the deep cleft at the active center. This corresponds to the
expected induced fit. Sequence comparisons with other adenylate kinases suggest
that one of the adenosine moieties of the inhibitor does not bind at a native
nucleotide-binding site of the enzyme.
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