1k68: Difference between revisions

[[Image:1k68.jpg|left|200px]]<br /><applet load="1k68" size="350" color="white" frame="true" align="right" spinBox="true"  

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.

1K68 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Tolypothrix_sp._pcc_7601 Tolypothrix sp. pcc 7601] with <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K68 OCA].  

[[Category: Marsac, N Tandeau de.]]

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