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Allosterically gated enzyme dynamics in the cysteine synthase complex regulate cysteine biosynthesis in Arabidopsis thaliana

Summary: Plants and bacteria assimilate sulfur into cysteine. Cysteine biosynthesis involves a bienzyme complex, the cysteine synthase complex (CSC), which consists of serine-acetyl-transferase (SAT) and O-acetyl-serine-(thiol)-lyase (OAS-TL) enzymes. The activity of OAS-TL is reduced by formation o...

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Bibliographic Details
Main Authors: Feldman-Salit, Anna (Author) , Wirtz, Markus (Author) , Throm, Christian (Author) , Hell, Rüdiger (Author) , Wade, Rebecca C. (Author)
Format: Article (Journal)
Language:English
Published: 8 Februar 2012
In: Structure
Year: 2012, Volume: 20, Issue: 2, Pages: 292-302
ISSN:1878-4186
DOI:10.1016/j.str.2011.11.019
Online Access:Verlag, kostenfrei, Volltext: http://dx.doi.org/10.1016/j.str.2011.11.019
Verlag, kostenfrei, Volltext: http://www.sciencedirect.com/science/article/pii/S0969212611004655
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Author Notes:Anna Feldman-Salit, Markus Wirtz, Esther D. Lenherr, Christian Throm, Michael Hothorn, Klaus Scheffzek, Rüdiger Hell, and Rebecca C. Wade
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Summary:Summary: Plants and bacteria assimilate sulfur into cysteine. Cysteine biosynthesis involves a bienzyme complex, the cysteine synthase complex (CSC), which consists of serine-acetyl-transferase (SAT) and O-acetyl-serine-(thiol)-lyase (OAS-TL) enzymes. The activity of OAS-TL is reduced by formation of the CSC. Although this reduction is an inherent part of the self-regulation cycle of cysteine biosynthesis, there has until now been no explanation as to how OAS-TL loses activity in plants. Complexation of SAT and OAS-TL involves binding of the C-terminal tail of SAT in one of the active sites of the homodimeric OAS-TL. We here explore the flexibility of the unoccupied active site in Arabidopsis thaliana cytosolic and mitochondrial OAS-TLs. Our results reveal two gates in the OAS-TL active site that define its accessibility. The observed dynamics of the gates show allosteric closure of the unoccupied active site of OAS-TL in the CSC, which can hinder substrate binding, abolishing its turnover to cysteine.
Item Description:Gesehen am: 18.05.2017
Physical Description:Online Resource
ISSN:1878-4186
DOI:10.1016/j.str.2011.11.019

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