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PDBsum entry 1k66
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Signaling protein
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PDB id
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1k66
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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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Crystal structures of two cyanobacterial response regulators in apo- And phosphorylated form reveal a novel dimerization motif of phytochrome-Associated response regulators.
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Authors
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C.Benda,
C.Scheufler,
N.Tandeau de marsac,
W.Gärtner.
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Ref.
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Biophys J, 2004,
87,
476-487.
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PubMed id
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Abstract
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The structures of two response regulators (RRs) from the cyanobacterium
Calothrix PCC7601, RcpA and RcpB, were solved to 1.9- and 1.75-A resolution,
respectively. RcpA was found in phosphorylated and RcpB in nonphosphorylated
form. Both RRs are members of phytochrome-associated, light-sensing
two-component signal transduction pathways, based on histidine kinase-mediated
receptor autophosphorylation and phosphorelay to a RR. Despite the overall
folding similarity to CheY-type RRs ((beta/alpha)(5)-motif), RcpA and RcpB form
homodimers, irrespective of their phosphorylation state, giving insight into a
signal transduction putatively different from that of other known RRs.
Dimerization is accomplished by a C-terminal extension of the RR polypeptide
chain, and the surface formed by H4, beta 5, and H5, which constitute a
hydrophobic contact area with distinct interactions between residues of either
subunit. Sequence alignments reveal that the identified dimerization motif is
archetypal for phytochrome-associated RRs, making them a novel subgroup of
CheY-type RRs. The protein structures of RcpA and RcpB are compared to the
recently presented protein structure of Rcp1 from Synechocystis.
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