1k68
Crystal Structure of the Phosphorylated Cyanobacterial Phytochrome Response Regulator RcpA
OverviewOverview
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.
About this StructureAbout this Structure
1K68 is a Single protein structure of sequence from Tolypothrix sp. pcc 7601. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of two cyanobacterial response regulators in apo- and phosphorylated form reveal a novel dimerization motif of phytochrome-associated response regulators., Benda C, Scheufler C, Tandeau de Marsac N, Gartner W, Biophys J. 2004 Jul;87(1):476-87. PMID:15240481 Page seeded by OCA on Fri May 2 22:21:29 2008