Title
Structural and functional insights into thermally stable cytochrome c’ from a thermophile
Author
Sotaro Fujii, Hiroya Oki, Kazuki Kawahara, Daisuke Yamane, Masaru Yamanaka, Takahiro Maruno, Yuji Kobayashi, Misa Masanari, Satoshi Wakai, Hirofumi Nishihara, Tadayasu Ohkubo, Yoshihiro Sambongi
Year
2017
Journal
Protein Science
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 subunit-subunit interactions with conservation of the ligand-binding ability.
Instrument
J-820
Keywords
Circular dichroism, Secondary structure, Thermal stability, Thermodynamics, Biochemistry