Cytochrome c" from the obligate methylotroph Methylophilus methylotrophus, an unexpected homolog of sphaeroides heme protein from the phototroph Rhodobacter sphaeroides.
The complete primary structure of an unusual soluble cytochrome c isolated from the obligate methylotrophic bacterium Methylophilus methylotrophus has been determined to contain 124 amino acids and to have an average molecular mass of 14293.0 Da. The sequence has two unusual features: firstly, the location of the heme-binding cysteines is far downstream from the N-terminus, namely at positions 49 and 52; secondly, an extra pair of cysteine residues is present near the C-terminus. In both respects, cytochrome c" is similar to the oxygen-binding heme protein SHP from the purple phototrophic bacterium Rhodobacter sphaeroides. In contrast to SHP, cytochrome c" changes from low-spin to high-spin upon reduction, due to dissociation of a sixth heme ligand histidine which is identified as His-95 by analogy to the class I cytochromes c. The distance of His-95 from the heme (41 residues) and the presence of certain consensus residues suggests that cytochrome c" is the second example of a variant class I cytochrome c.
Klarskov
K
K
Department of Biochemistry, Physiology and Microbiology, Laboratory of Protein Biochemistry and Protein Engineering, State University of Gent, Ledeganckstraat 35, B-9000, Gent, Belgium.
Leys
D
D
Backers
K
K
Costa
H S
HS
Santos
H
H
Guisez
Y
Y
Van Beeumen
J J
JJ
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D003574:Cytochrome c Group / Q000737:chemistry* / Q000302:isolation & purification; D006420:Hemeproteins / Q000737:chemistry* / Q000302:isolation & purification; D008666:Metalloendopeptidases; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D006420:Hemeproteins; D010446:Peptide Fragments; C076615:cytochrome c''; D008666:Metalloendopeptidases; C039830:peptidyl-Lys metalloendopeptidase