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.
Submitter: Shu-Ching Ou
Submission Date: Aug. 28, 2018, 3:31 p.m.
|Number of data points||55|
|Proteins||Thermophilic Hydrogenophilus thermoluteolus cytochrome c'|
|Assays/Quantities/Protocols||Experimental Assay: Thermal stability (Tm) ; Experimental Assay: Difference in free energy changes of denaturation between variant and wild-type ; Derived Quantity: SD of Thermal stability (Tm) ; Derived Quantity: Thermal stability (ΔTm) ; Derived Quantity: SD of Difference in free energy changes of denaturation between variant and wild-type|
|Libraries||Thermal stability measurement|