2XLE

Cytochrome c prime from Alcaligenes xylosoxidans: Ferrous R124K variant with bound NO

Summary for 2XLE

• Entry DOI: 10.2210/pdb2xle/pdb
• Related: 1CGN 1CGO 1E83 1E84 1E85 1E86 2XL5 2XL6 2XL8 2XLD 2XLH 2XLM 2XLO
• Descriptor: CYTOCHROME C', HEME C, NITRIC OXIDE, ... (5 entities in total)
• Functional Keywords: electron transport, haemoprotein, 4-helix bundle
• Biological source: ACHROMOBACTER XYLOSOXIDANS
• Total number of polymer chains: 1
• Total formula weight: 14348.00

Authors

Hough, M.A.,Antonyuk, S.V.,Hasnain, S.S. (deposition date: 2010-07-20, release date: 2010-11-10, Last modification date: 2024-10-16)

Primary citation

Hough, M.A.,Antonyuk, S.V.,Barbieri, S.,Rustage, N.,Mckay, A.L.,Servid, A.E.,Eady, R.R.,Andrew, C.R.,Hasnain, S.S.
Distal-to-Proximal No Conversion in Hemoproteins: The Role of the Proximal Pocket.
J.Mol.Biol., 405:395-, 2011

PubMed Abstract: Hemoproteins play central roles in the formation and utilization of nitric oxide (NO) in cellular signaling, as well as in protection against nitrosative stress. Key to heme-nitrosyl function and reactivity is the Fe coordination number (5 or 6). For (five-coordinate) 5c-NO complexes, the potential for NO to bind on either heme face exists, as in the microbial cytochrome c' from Alcaligenes xylosoxidans (AxCYTcp), which forms a stable proximal 5c-NO complex via a distal six-coordinate NO intermediate and a putative dinitrosyl species. Strong parallels between the NO-binding kinetics of AxCYTcp, the eukaryotic NO sensor soluble guanylate cyclase, and the ferrocytochrome c/cardiolipin complex have led to the suggestion that a distal-to-proximal NO switch could contribute to the selective ligand responses in gas-sensing hemoproteins. The proximal NO-binding site in AxCYTcp is close to a conserved basic (Arg124) residue that is postulated to modulate NO reactivity. We have replaced Arg124 by five different amino acids and have determined high-resolution (1.07-1.40 Å) crystallographic structures with and without NO. These, together with kinetic and resonance Raman data, provide new insights into the mechanism of distal-to-proximal heme-NO conversion, including the determinants of Fe-His bond scission. The Arg124Ala variant allowed us to determine the structure of an analog of the previously unobserved key 5c-NO distal intermediate species. The very high resolution structures combined with the extensive spectroscopic and kinetic data have allowed us to provide a fresh insight into heme reactivity towards NO, a reaction that is of wide importance in biology.

PubMed: 21073879
DOI: 10.1016/J.JMB.2010.10.035

Experimental method

X-RAY DIFFRACTION (1.12 Å)