Yang, Ming-Jun and Pang, Xue-Qin and Zhang, Xin and Han, Ke-Li (2011) Molecular dynamics simulation reveals preorganization of the chloroplast FtsY towards complex formation induced by GTP binding. Journal of Structural Biology, 173 (1). pp. 57-66. ISSN 1047-8477 http://resolver.caltech.edu/CaltechAUTHORS:20110304-074818379
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Two GTPases in the signal recognition particle (SRP) and SRP receptor (SR) interact with one another to mediate the cotranslational protein targeting pathway. Previous studies have shown that a universally conserved SRP RNA facilitates an efficient SRP–SR interaction in the presence of a signal sequence bound to SRP. However, a remarkable exception has been found in chloroplast SRP (cpSRP) pathway, in which the SRP RNA is missing. Based on biochemical and structural analyses, it is proposed that free cpSRP receptor (cpFtsY) has already been preorganized into a closed state for efficient cpSRP–cpFtsY association. However, no direct evidence has been reported to support this postulation thus far. In this study, we characterized the structural dynamics of cpFtsY and its conformational rearrangements induced by GTP binding using molecular dynamics (MD) simulations. Our results showed that the GTP-binding event triggered substantial conformational changes in free cpFtsY, including the relative orientation of N–G domain and several conserved motifs that are critical in complex formation. These rearrangements enabled the cpFtsY to relax into a preorganized ‘closed’ state that favored the formation of a stable complex with cpSRP54. Interestingly, the intrinsic flexibility of aN1 helix facilitated these rearrangements. In addition, GTP binding in cpFtsY was mediated by conserved residues that have been shown in other SRP GTPases. These findings suggested that GTP-bound cpFtsY could fluctuate into conformations that are favorable to form the stable complex, providing explanation of why SRP–SR interaction bypasses the requirement of the SRP RNA at a molecular level.
|Additional Information:||© 2010 Elsevier Inc. Received 8 May 2010; revised 19 July 2010; accepted 27 July 2010. Available online 2 August 2010. The authors thank F.Y. Dupradeau for providing the atomic charges of GTP used in simulation of the GTP–cpFtsY. Both simulations were performed on deepcomp 7000 supercomputer at Supercomputer Center of the Chinese Academy of Sciences. This work was supported by NKBRSF (No. 2007CB815202) and 863 (No. 2006AA01A119).|
|Subject Keywords:||Signal recognition particle; SRP GTPase; Protein targeting reaction; Chloroplast SRP system; Protein–protein interaction|
|Official Citation:||Ming-Jun Yang, Xue-Qin Pang, Xin Zhang, Ke-Li Han, Molecular dynamics simulation reveals preorganization of the chloroplast FtsY towards complex formation induced by GTP binding, Journal of Structural Biology, Volume 173, Issue 1, January 2011, Pages 57-66, ISSN 1047-8477, DOI: 10.1016/j.jsb.2010.07.013. (http://www.sciencedirect.com/science/article/B6WM5-50NYWTY-4/2/44b36354d6b6d84d194280188a3f48f1)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||04 Mar 2011 17:03|
|Last Modified:||04 Mar 2011 17:03|
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