First time at Proteopedia? Click on the green links: they change the 3D image. Click and drag the molecules. Proteopedia is a 3D, interactive encyclopedia of proteins, RNA, DNA and other molecules. With a free user account, you can edit pages in Proteopedia. Visit the Main Page to learn more.
|2nu7, resolution 2.20Å ()|
|Gene:||sucD (Escherichia coli), sucC (Escherichia coli)|
|Related:||1jkj, 1jll, 2nu6, 2nu8, 2nu9, 2nua|
C123aS Mutant of E. coli Succinyl-CoA Synthetase
Succinyl-CoA synthetase has a highly conserved cysteine residue, Cys123alpha in the Escherichia coli enzyme, that is located near the CoA-binding site and the active-site histidine residue. To test whether the succinyl moiety of succinyl-CoA is transferred to the thiol of Cys123alpha as part of the catalytic mechanism, this residue was mutated to alanine, serine, threonine and valine. Each mutant protein was catalytically active, although less active than the wild type. This proved that the specific formation of a thioester bond with Cys123alpha is not part of the catalytic mechanism. To understand why the mutations affected catalysis, the crystal structures of the four mutant proteins were determined. The alanine mutant showed no structural changes yet had reduced activity, suggesting that the size of the cysteine is important for optimal activity. These results explain why this cysteine residue is conserved in the sequences of succinyl-CoA synthetases from different sources.
Participation of Cys123alpha of Escherichia coli succinyl-CoA synthetase in catalysis., Hidber E, Brownie ER, Hayakawa K, Fraser ME, Acta Crystallogr D Biol Crystallogr. 2007 Aug;63(Pt 8):876-84. Epub 2007, Jul 17. PMID:17642514
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
- Hidber E, Brownie ER, Hayakawa K, Fraser ME. Participation of Cys123alpha of Escherichia coli succinyl-CoA synthetase in catalysis. Acta Crystallogr D Biol Crystallogr. 2007 Aug;63(Pt 8):876-84. Epub 2007, Jul 17. PMID:17642514 doi:10.1107/S0907444907029319
Page seeded by OCA on Wed Feb 18 09:12:32 2009