5JP7

Ferrous Leu 16 Val mutant of cytochrome c prime from Alcaligenes xylosoxidans

Summary for 5JP7

• Entry DOI: 10.2210/pdb5jp7/pdb
• Descriptor: Cytochrome c', HEME C (3 entities in total)
• Functional Keywords: gas sensor cytochrome nitric oxide, electron transport
• Biological source: Alcaligenes xylosoxydans xylosoxydans
• Total number of polymer chains: 1
• Total formula weight: 14106.74

Authors

Kekilli, D.,Strange, R.W.,Hough, M.A. (deposition date: 2016-05-03, release date: 2017-03-08, Last modification date: 2024-11-13)

Primary citation

Kekilli, D.,Petersen, C.A.,Pixton, D.A.,Ghafoor, D.D.,Abdullah, G.H.,Dworkowski, F.S.N.,Wilson, M.T.,Heyes, D.J.,Hardman, S.J.O.,Murphy, L.M.,Strange, R.W.,Scrutton, N.S.,Andrew, C.R.,Hough, M.A.
Engineering proximal vs. distal heme-NO coordination via dinitrosyl dynamics: implications for NO sensor design.
Chem Sci, 8:1986-1994, 2017

PubMed Abstract: Proximal distal heme-NO coordination is a novel strategy for selective gas response in heme-based NO-sensors. In the case of cytochrome c' (AXCP), formation of a transient distal 6cNO complex is followed by scission of the Fe-His bond and conversion to a proximal 5cNO product a putative dinitrosyl species. Here we show that replacement of the AXCP distal Leu16 residue with smaller or similar sized residues (Ala, Val or Ile) traps the distal 6cNO complex, whereas Leu or Phe residues lead to a proximal 5cNO product with a transient or non-detectable distal 6cNO precursor. Crystallographic, spectroscopic, and kinetic measurements of 6cNO AXCP complexes show that increased distal steric hindrance leads to distortion of the Fe-N-O angle and flipping of the heme 7-propionate. However, it is the kinetic parameters of the distal NO ligand that determine whether 6cNO or proximal 5cNO end products are formed. Our data support a 'balance of affinities' mechanism in which proximal 5cNO coordination depends on relatively rapid release of the distal NO from the dinitrosyl precursor. This mechanism, which is applicable to other proteins that form transient dinitrosyls, represents a novel strategy for 5cNO formation that does not rely on an inherently weak Fe-His bond. Our data suggest a general means of engineering selective gas response into biologically-derived gas sensors in synthetic biology.

PubMed: 28451315
DOI: 10.1039/c6sc04190f

Experimental method

X-RAY DIFFRACTION (1.26 Å)