Rubredoxin and a novel membrane bound cytochrome C(553) from the photosynthetic bacterium, Heliobacillus mobilis

The recently described heliobacteria have attracted considerable attention due to their ancestral features in viewpoints of both photosynthesis and the gram-positive phenotypes. Biologically important electron carriers, rubredoxin and a membrane bound cytochrome c;The membrane-bound cytochrome ;The sequences of these two electron transfer proteins are closely related to those found in gram-positive bacteria and the phototrophic green sulfur bacteria, and the evolutionary implications of this are discussed.;Rubredoxin is a small non-heme iron protein that serves as an electron carrier in many bacterial systems. This protein was isolated from Hc. mobilis and characterized. The molecular mass (5671.3 Da from the amino acid sequence) of the heliobacterial rubredoxin was confirmed and partial formylation of the N-terminal methionyl residue was established by matrix-assisted laser desorption mass spectroscopy. The complete 52 amino acid sequence was determined by a combination of N-terminal sequencing by Edman degradation and C-terminal sequencing by a novel method using carboxypeptidase treatment in conjunction with amino acid analysis and laser desorption time of flight mass spectrometry. The molecular absorption coefficient of Hc. mobilis rubredoxin at 490 nm is 6.9 mM...