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PDBsum entry 1euc
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Phosphorylated and dephosphorylated structures of pig heart, Gtp-Specific succinyl-Coa synthetase.
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Authors
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M.E.Fraser,
M.N.James,
W.A.Bridger,
W.T.Wolodko.
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Ref.
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J Mol Biol, 2000,
299,
1325-1339.
[DOI no: ]
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PubMed id
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Abstract
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Succinyl-CoA synthetase (SCS) catalyzes the reversible
phosphorylation/dephosphorylation reaction:¿¿¿rm succinyl ¿hbox
¿-¿CoA+NDP+P_i¿leftrightarrow succinate+CoA+NTP¿¿where N denotes adenosine
or guanosine. In the course of the reaction, an essential histidine residue is
transiently phosphorylated. We have crystallized and solved the structure of the
GTP-specific isoform of SCS from pig heart (EC 6.2.1.4) in both the
dephosphorylated and phosphorylated forms. The structures were refined to 2.1 A
resolution. In the dephosphorylated structure, the enzyme is stabilized via
coordination of a phosphate ion by the active-site histidine residue and the two
"power" helices, one contributed by each subunit of the
alphabeta-dimer. Small changes in the conformations of residues at the amino
terminus of the power helix contributed by the alpha-subunit allow the enzyme to
accommodate either the covalently bound phosphoryl group or the free phosphate
ion. Structural comparisons are made between the active sites in these two forms
of the enzyme, both of which can occur along the catalytic path. Comparisons are
also made with the structure of Escherichia coli SCS. The domain that has been
shown to bind ADP in E. coli SCS is more open in the pig heart, GTP-specific SCS
structure.
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Figure 1.
Figure 1. Pig heart, GTP-specific SCS. In this
three-dimensional ribbon diagram, the a-subunit is white, with
light gray for the interior of the helices, and the side-chain
of the active site phosphohistidine residue is shown as a
ball-and-stick model; the b-subunit is shaded gray, as are the
two sulfate ions. The amino and carboxy termini of each subunit
are labeled N and C, respectively. This Figure and Figure 2 and
Figure 7 were drawn using the program MOLSCRIPT (Kraulis, 1991).
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Figure 2.
Figure 2. Stereo diagrams of the regions surrounding the
active-site histidine residue. The residues are shown as
ball-and-stick models. Hydrogen-bonding interactions with the
oxygen atoms of the phosphate ion or the phosporyl group are
represented by broken lines. (a) Dephosphorylated pig heart,
GTP-specific SCS. (b) Phosphorylated pig heart, GTP-specific SCS.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2000,
299,
1325-1339)
copyright 2000.
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