3ZQY

CYTOCHROME C PRIME FROM ALCALIGENES XYLOSOXIDANS: CARBON MONOOXIDE BOUND L16A VARIANT AT 1.03 A RESOLUTION- NON-RESTRAINT REFINEMENT

Summary for 3ZQY

• Entry DOI: 10.2210/pdb3zqy/pdb
• Related: 1CGN 1CGO 1E83 1E84 1E85 1E86 2XL6 2XL8 2XLD 2XLE 2XLH 2XLM 2XLO 2XLV 2XLW 2XM0 2XM4 2YKZ 2YL0 2YL1 2YL3 2YL7 2YLD 2YLG 2YLI 3ZQV
• Descriptor: CYTOCHROME C', HEME C, CARBON MONOXIDE, ... (4 entities in total)
• Functional Keywords: electron transport, haemoprotein, 4-helix bundle
• Biological source: ACHROMOBACTER XYLOSOXIDANS
• Total number of polymer chains: 1
• Total formula weight: 14235.88

Authors

Antonyuk, S.V.,Rustage, N.,Eady, R.R.,Hasnain, S.S. (deposition date: 2011-06-12, release date: 2011-10-05, Last modification date: 2024-10-23)

Primary citation

Antonyuk, S.V.,Rustage, N.,Petersen, C.A.,Arnst, J.L.,Heyes, D.J.,Sharma, R.,Berry, N.G.,Scrutton, N.S.,Eady, R.R.,Andrew, C.R.,Hasnain, S.S.
Carbon Monoxide Poisoning is Prevented by the Energy Costs of Conformational Changes in Gas- Binding Haemproteins.
Proc.Natl.Acad.Sci.USA, 108:15780-, 2011

PubMed Abstract: Carbon monoxide (CO) is a product of haem metabolism and organisms must evolve strategies to prevent endogenous CO poisoning of haemoproteins. We show that energy costs associated with conformational changes play a key role in preventing irreversible CO binding. AxCYTcp is a member of a family of haem proteins that form stable 5c-NO and 6c-CO complexes but do not form O(2) complexes. Structure of the AxCYTcp-CO complex at 1.25 Å resolution shows that CO binds in two conformations moderated by the extent of displacement of the distal residue Leu16 toward the haem 7-propionate. The presence of two CO conformations is confirmed by cryogenic resonance Raman data. The preferred linear Fe-C-O arrangement (170 ± 8°) is accompanied by a flip of the propionate from the distal to proximal face of the haem. In the second conformation, the Fe-C-O unit is bent (158 ± 8°) with no flip of propionate. The energetic cost of the CO-induced Leu-propionate movements is reflected in a 600 mV (57.9 kJ mol(-1)) decrease in haem potential, a value in good agreement with density functional theory calculations. Substitution of Leu by Ala or Gly (structures determined at 1.03 and 1.04 Å resolutions) resulted in a haem site that binds CO in the linear mode only and where no significant change in redox potential is observed. Remarkably, these variants were isolated as ferrous 6c-CO complexes, attributable to the observed eight orders of magnitude increase in affinity for CO, including an approximately 10,000-fold decrease in the rate of dissociation. These new findings have wide implications for preventing CO poisoning of gas-binding haem proteins.

PubMed: 21900609
DOI: 10.1073/PNAS.1109051108

Experimental method

X-RAY DIFFRACTION (1.03 Å)