Cytochromes c of Campylobacter sputorum subspecies mucosalis

Abstract

Campylobacter sputorum subspecies mucosalis, the causative organism of porcine intestinal adenomatosis, will grow microaerophillically in the presence of hydrogen as an electron donor, and under these conditions contains a high complement of c-type cytochromes. The cytochromes c in a crude extract of the organism were examined by redox potentiometry. The redox potentiometric data were consistent with the presence of at least two low midpoint potential and two high midpoint potential cytochromes c. Furthermore the prediction could be made that one of the high midpoint potential cytochromes contains an asymmetric α-peak. A high midpoint potential cytochrome c was isolated and then characterized with respect to its spectrum, midpoint potential, amino acid composition and N-terminal sequence. The pure cytochrome was shown to exhibit a midpoint potential close to that predicted from titration of the crude preparations and to possess a markedly asymmetric α-peak. The cytochrome exhibits similarities to a number of high midpoint potential low spin cytochromes c and has been compared to these. Partial isolation and characterization of three low midpoint potential low spin cytochromes c was possible. These cytochromes (the cytochromes c552) show no similarity to other low potential cytochromes c reported in the literature with respect to spectrum and molecular weights and are apparently unique to the organism. The presence of both low midpoint and high midpoint potential cytochromes c has so far been reported for only a few organisms, including members of the genus Campylobacter. In the light of the redox potentiometric data, the electron transport chain of Campylobacter sputorum subspecies mucosalis has been compared to those of other well studied organisms.