2og2
Crystal structure of chloroplast FtsY from Arabidopsis thalianaCrystal structure of chloroplast FtsY from Arabidopsis thaliana
Structural highlights
Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe signal recognition particle (SRP) pathway mediates co-translational targeting of nascent proteins to membranes. Chloroplast SRP is unique in that it does not contain the otherwise universally conserved SRP RNA, which accelerates the association between the SRP guanosine-5'-triphosphate (GTP) binding protein and its receptor FtsY in classical SRP pathways. Recently, we showed that the SRP and SRP receptor (SR) GTPases from chloroplast (cpSRP54 and cpFtsY, respectively) can interact with one another 400-fold more efficiently than their bacterial homologues, thus providing an explanation as to why this novel chloroplast SRP pathway bypasses the requirement for the SRP RNA. Here we report the crystal structure of cpFtsY from Arabidopsis thaliana at 2.0 A resolution. In this chloroplast SR, the N-terminal "N" domain is more tightly packed, and a more extensive interaction surface is formed between the GTPase "G" domain and the N domain than was previously observed in many of its bacterial homologues. As a result, the overall conformation of apo-cpFtsY is closer to that found in the bacterial SRP*FtsY complex than in free bacterial FtsY, especially with regard to the relative orientation of the N and G domains. In contrast, active-site residues in the G domain are mispositioned, explaining the low basal GTP binding and hydrolysis activity of free cpFtsY. This structure emphasizes proper N-G domain arrangement as a key factor in modulating the efficiency of SRP-receptor interaction and helps account, in part, for the faster kinetics at which the chloroplast SR interacts with its binding partner in the absence of an SRP RNA. Structure of the chloroplast signal recognition particle (SRP) receptor: domain arrangement modulates SRP-receptor interaction.,Chandrasekar S, Chartron J, Jaru-Ampornpan P, Shan SO J Mol Biol. 2008 Jan 11;375(2):425-36. Epub 2007 Nov 26. PMID:18035371[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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