| Structural highlights
Function
[CYSKM_ARATH] Acts as a cysteine synthase. Plays a role in the sulfide detoxification in mitochondria.[1] [2] [3]
Publication Abstract from PubMed
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.
Allosterically Gated Enzyme Dynamics in the Cysteine Synthase Complex Regulate Cysteine Biosynthesis in Arabidopsis thaliana.,Feldman-Salit A, Wirtz M, Lenherr ED, Throm C, Hothorn M, Scheffzek K, Hell R, Wade RC Structure. 2012 Feb 8;20(2):292-302. PMID:22325778[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Watanabe M, Kusano M, Oikawa A, Fukushima A, Noji M, Saito K. Physiological roles of the beta-substituted alanine synthase gene family in Arabidopsis. Plant Physiol. 2008 Jan;146(1):310-20. Epub 2007 Nov 16. PMID:18024555 doi:https://dx.doi.org/10.1104/pp.107.106831
- ↑ Heeg C, Kruse C, Jost R, Gutensohn M, Ruppert T, Wirtz M, Hell R. Analysis of the Arabidopsis O-acetylserine(thiol)lyase gene family demonstrates compartment-specific differences in the regulation of cysteine synthesis. Plant Cell. 2008 Jan;20(1):168-85. doi: 10.1105/tpc.107.056747. Epub 2008 Jan 25. PMID:18223034 doi:https://dx.doi.org/10.1105/tpc.107.056747
- ↑ Alvarez C, Garcia I, Romero LC, Gotor C. Mitochondrial sulfide detoxification requires a functional isoform O-acetylserine(thiol)lyase C in Arabidopsis thaliana. Mol Plant. 2012 Nov;5(6):1217-26. doi: 10.1093/mp/sss043. Epub 2012 Apr 17. PMID:22511607 doi:https://dx.doi.org/10.1093/mp/sss043
- ↑ Feldman-Salit A, Wirtz M, Lenherr ED, Throm C, Hothorn M, Scheffzek K, Hell R, Wade RC. Allosterically Gated Enzyme Dynamics in the Cysteine Synthase Complex Regulate Cysteine Biosynthesis in Arabidopsis thaliana. Structure. 2012 Feb 8;20(2):292-302. PMID:22325778 doi:https://dx.doi.org/10.1016/j.str.2011.11.019
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