期刊
PROTEIN SCIENCE
卷 26, 期 4, 页码 737-748出版社
WILEY
DOI: 10.1002/pro.3120
关键词
protein stability; cytochrome c; thermophile; protein structure; mutagenesis; ligand-binding
资金
- Grants-in-Aid for Scientific Research [15J06345] Funding Source: KAKEN
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 angstrom. 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. Brief SummaryWe report the X-ray crystal structure of cytochrome c (PHCP) from thermophilic Hydrogenophilus thermoluteolus. The high thermal stability of PHCP was attributed to heme-related and subunit-subunit interactions, which were confirmed by a mutagenesis study. The ligand-binding ability of PHCP was examined by spectrophotometry. PHCP acquired the thermal stability with conservation of the ligand-binding ability. This study furthers the understanding of the stability and function of cytochromes c.
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