2NU6

C123aA Mutant of E. coli Succinyl-CoA Synthetase

Summary for 2NU6

• Entry DOI: 10.2210/pdb2nu6/pdb
• Related: 1JKJ 1JLL 2NU7 2NU8 2NU9 2NUA 2SCU
• Descriptor: Succinyl-CoA ligase [ADP-forming] subunit alpha, Succinyl-CoA synthetase beta chain, SULFATE ION, ... (5 entities in total)
• Functional Keywords: citric acid cycle, heterotetramer, ligase, atp-grasp fold, rossmann fold
• Biological source: Escherichia coli; More
• Total number of polymer chains: 4
• Total formula weight: 147318.74

Authors

Fraser, M.E. (deposition date: 2006-11-08, release date: 2007-07-24, Last modification date: 2023-08-30)

Primary citation

Hidber, E.,Brownie, E.R.,Hayakawa, K.,Fraser, M.E.
Participation of Cys 123alpha of Escherichia coli Succinyl-CoA Synthetase in Catalysis
ACTA CRYSTALLOGR.,SECT.D, 63:876-884, 2007

PubMed Abstract: 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.

PubMed: 17642514
DOI: 10.1107/S0907444907029319

Experimental method

X-RAY DIFFRACTION (2.55 Å)