Identification of the Active Conformation and the Importance of Length of the Flexible Loop 72-83 in Regulating the Conformational Change of Undecaprenyl Pyrophosphate Synthase

Sing Yang Chang, Yi Kai Chen, Andrew H.J. Wang, Po Huang Liang

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17 引文 斯高帕斯(Scopus)

摘要

Increasing evidence has shown that intrinsic disorder of proteins plays a key role in their biological functions. In the case of undecaprenyl pyrophosphate synthase (UPPs), which catalyzes the chain elongation of farnesyl pyrophosphate (FPP) to undecaprenyl pyrophosphate via eight consecutive condensation reactions with isopentenyl pyrophosphate, a highly flexible loop 72-83 was previously linked to protein conformational change required for catalysis [Chen, Y. H., Chen, A. P.-C., Chen, C. T., Wang, A. H.-J., and Liang, P. H., (2002) J. Biol. Chem. 277, 7369-7376]. The crystal structure and fluorescence studies suggested that the α3 helix connected to the loop moves toward the active site when the substrate is bound. To identify the active conformation and study the role of the loop for conformational change, the UPPs mutants with amino acids inserted into or deleted from the loop were examined. The inserted mutant with extra Ala residues fails to display the intrinsic fluorescence quenching upon FPP binding, and its crystal structure reveals only the open form. These phenomena appear to be different from the wild-type enzyme in which open and closed conformers were observed and suggest that the extended loop fails to pull the α3 helix and/or the extra amino acids in the loop cause steric hindrance on the α3 helix movement. The loop-shortening mutants with deletion of V82 and S83 or S72 also adopt an open conformation with the loop stretched, although they show decreased intrinsic fluorescence with FPP bound, similar to that seen in the wild-type enzyme. We conclude that the closed conformation is apparently the active conformation. Change of the length of the loop 72-83 impairs the ability of conformational change and causes remarkably lower activity of UPPs.

原文英語
頁(從 - 到)14452-14459
頁數8
期刊Biochemistry
42
發行號49
DOIs
出版狀態已發佈 - 12月 16 2003
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ASJC Scopus subject areas

  • 生物化學

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