Abstract

Thermophilic Hydrogenophilus thermoluteolus cytochrome c' (PHCP) exhibits higher thermal stability than a mesophilic counterpart, Allochromatium vinosum cytochrome c' (AVCP), which has a homo-dimeric structure and ligand-binding ability. To understand the thermal stability mechanism and ligand-binding ability of the thermally stable PHCP protein, the crystal structure of PHCP was first determined. It formed a homo-dimeric structure, the main chain root mean square deviation (rmsd) value between PHCP and AVCP being 0.65 Å. In the PHCP structure, six specific residues appeared to strengthen the heme-related and subunit-subunit interactions, which were not conserved in the AVCP structure. PHCP variants having altered subunit-subunit interactions were more severely destabilized than ones having altered heme-related interactions. The PHCP structure further revealed a ligand-binding channel and a penta-coordinated heme, as observed in the AVCP protein. A spectroscopic study clearly showed that some ligands were bound to the PHCP protein. It is concluded that the dimeric PHCP from the thermophile is effectively stabilized through heme-related and subunit-subunit interactions with conservation of the ligand-binding ability.

Submission Details

ID: FyFTmMCT4

Submitter: Shu-Ching Ou

Submission Date: Aug. 28, 2018, 3:31 p.m.

Version: 1

Publication Details

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