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PDBsum entry 1cs4
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Lyase/lyase/signaling protein
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PDB id
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1cs4
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Contents |
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189 a.a.
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190 a.a.
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329 a.a.
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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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Molecular basis for p-Site inhibition of adenylyl cyclase.
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Authors
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J.J.Tesmer,
C.W.Dessauer,
R.K.Sunahara,
L.D.Murray,
R.A.Johnson,
A.G.Gilman,
S.R.Sprang.
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Ref.
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Biochemistry, 2000,
39,
14464-14471.
[DOI no: ]
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PubMed id
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Abstract
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P-site inhibitors are adenosine and adenine nucleotide analogues that inhibit
adenylyl cyclase, the effector enzyme that catalyzes the synthesis of cyclic AMP
from ATP. Some of these inhibitors may represent physiological regulators of
adenylyl cyclase, and the most potent may ultimately serve as useful therapeutic
agents. Described here are crystal structures of the catalytic core of adenylyl
cyclase complexed with two such P-site inhibitors, 2'-deoxyadenosine
3'-monophosphate (2'-d-3'-AMP) and 2',5'-dideoxyadenosine 3'-triphosphate
(2',5'-dd-3'-ATP). Both inhibitors bind in the active site yet exhibit non- or
uncompetitive patterns of inhibition. While most P-site inhibitors require
pyrophosphate (PP(i)) as a coinhibitor, 2',5'-dd-3'-ATP is a potent inhibitor by
itself. The crystal structure reveals that this inhibitor exhibits two binding
modes: one with the nucleoside moiety bound to the nucleoside binding pocket of
the enzyme and the other with the beta and gamma phosphates bound to the
pyrophosphate site of the 2'-d-3'-AMP.PP(i) complex. A single metal binding site
is observed in the complex with 2'-d-3'-AMP, whereas two are observed in the
complex with 2', 5'-dd-3'-ATP. Even though P-site inhibitors are typically 10
times more potent in the presence of Mn(2+), the electron density maps reveal no
inherent preference of either metal site for Mn(2+) over Mg(2+). 2',5'-dd-3'-ATP
binds to the catalytic core of adenylyl cyclase with a K(d) of 2.4 microM in the
presence of Mg(2+) and 0.2 microM in the presence of Mn(2+). Pyrophosphate does
not compete with 2',5'-dd-3'-ATP and enhances inhibition.
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Secondary reference #1
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Title
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Crystal structure of the catalytic domains of adenylyl cyclase in a complex with gsalpha.Gtpgammas.
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Authors
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J.J.Tesmer,
R.K.Sunahara,
A.G.Gilman,
S.R.Sprang.
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Ref.
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Science, 1997,
278,
1907-1916.
[DOI no: ]
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PubMed id
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Figure 1.
Fig. 1. Architecture of the heterodimeric complex between
VC[1] (mauve) and IIC[2] (khaki) bound to the forskolin analog
MPFsk, as observed^ in the complex with G[s][  ]·GTP
 S. (A)
View along the pseudo-twofold^ axis toward the ventral surface
of VC[1]·IIC[2]. The forskolin derivative^ is shown as a
stick figure: carbon, gray; nitrogen, cyan; and^ oxygen, red. N
and C mark the first and last ordered residues^ in the crystal
structure of the heterodimer. (B) VC[1] is^ depicted
side-by-side with a molecule of IIC[2] that has been
superimposed^ on VC[1] (rmsd of 1.3 Å for 153 C  atom
pairs). Elements of secondary^ structure are labeled; in all of
the figures, the color of the^ label identifies the protein
subunit to which it refers. (C)^ Stereo diagram of the
VC[1]·IIC[2] interface, with the C backbone^
depicted as a continuous tube. The view is the same as in (A).^
Ball-and-stick models of C  C  bonds are
shown for residues (50)^ that participate in interdomain
contacts (separated by less than^ 4 Å from an atom in the
opposite domain). These residues constitute^ the subset of
interfacial residues that are conserved in all adenylyl^ cyclase
isoforms. C atoms of
residues with acidic side chains^ are red, basic residues are
blue, and residues with polar side^ chains are pink. The C atoms of
nonpolar residues are khaki (VC[1])^ or mauve (IIC[2]). Dashed
gray lines show interdomain side chain-side^ chain or side
chain-main chain hydrogen bonds or ion pairs involving^ polar
or charged interfacial residues. Only the polar or charged^
residues are labeled.
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Figure 3.
Fig. 3. Only one molecule of forskolin binds in the ventral
cleft of VC[1]·IIC[2]. MPFsk binds in the ventral cleft
of adenylyl cyclase^ at the end closest to the G[s][ ]binding
site and is drawn in^ green without its methyl-piperazino group
for clarity. Residues^ constituting the forskolin binding site
of the IIC[2] homodimer^ (14) that differ from their equivalents
in the binding site^ of VC[1]·IIC[2] are drawn in
transparent rose (50). The side chain^ of Trp^1020 is also shown
because its side chain adopts a dramatically different^
conformation from that of Trp^507 in the VC[1]·IIC[2]
heterodimer. To generate this figure, we superimposed^ one of
the forskolin molecules from the IIC[2] homodimer with MPFsk;^
this superposition does not optimally align the protein
subunits^ of each structure.
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The above figures are
reproduced from the cited reference
with permission from the AAAs
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