Spectroscopic Interrogation of Thiolate Hydrogen Bonding in the CO Sensor Protein CooA: Implications for Thiolate Ligation Stability and Cytochrome P450 Function.

ABSTRACT: Cysteine (Cys) thiolate coordination in hemoproteins is a unique ligation motif found in enzymes and small molecule sensors. It is posited that divergence between these two functional classes of heme thiolate proteins is a result of distinct hydrogen bonding (H-bonding) interactions with the axial Cys(thiolate) ligand. To further test this hypothesis, we report a spectroscopic analysis of thiolate H-bonding in CooA, a carbon monoxide-sensing heme protein from Rhodospirillum rubrum that is known to switch between Cys⁷⁵(thiolate) and histidine coordination upon reduction. We generated CooA variants with alterations at two residues, Asn⁴² and His⁷⁷, which are postulated to influence H-bonding to Cys⁷⁵ on the basis of an Fe(II) CooA structure. Using

SUBMITTER: Weaver BR 

PROVIDER: S-EPMC12223480 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature