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PDBsum entry 1v3r
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Signaling protein
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PDB id
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1v3r
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References listed in PDB file
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Key reference
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Title
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Crystal structures of the signal transducing protein glnk from thermus thermophilus hb8.
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Authors
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H.Sakai,
H.Wang,
C.Takemoto-Hori,
T.Kaminishi,
H.Yamaguchi,
Y.Kamewari,
T.Terada,
S.Kuramitsu,
M.Shirouzu,
S.Yokoyama.
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Ref.
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J Struct Biol, 2005,
149,
99.
[DOI no: ]
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PubMed id
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Abstract
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The Thermus thermophilus HB8 genome encodes a signal transducing PII protein,
GlnK. The crystal structures of GlnK have been determined in two different space
groups, P2(1)2(1)2(1) and P3(1)21. The PII protein has the T-loop, which is
essential for interactions with receptor proteins. In both crystal forms, three
GlnK molecules form a trimer in the asymmetric unit. In one P2(1)2(1)2(1)
crystal form, the three T-loops in the trimer are disordered, while in another
P2(1)2(1)2(1) crystal form, the T-loop from one molecule in the trimer is
ordered. In the P3(1)21 crystal, one T-loop is ordered while the other two
T-loops are disordered. The conformations of the ordered T-loops significantly
differ between the two crystal forms; one makes the alpha-helix in the middle of
the T-loop, while the other has an extension of the beta-hairpin. Two different
conformations are captured by the crystal contacts. The observation of multiple
T-loop conformations suggests that the T-loop could potentially exhibit
"polysterism," which would be important for interactions with receptor proteins.
The crystal structures of the nucleotide-bound forms, GlnK.ATP and GlnK.ADP,
have also been determined. ATP/ADP binding within a cleft at the interface of
two adjacent T. thermophilus GlnK monomers might affect the conformation of the
T-loop.
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