The Respiratory Chain In Neisseria Species

This work presents the organization of respiratory chain in Neisseria species. The localization of redox proteins was determined. Lipid-modified azurin (Laz) and nitrite reductase (AniA) are mainly associated with outer membrane. All c-type cytochrome proteins are mainly associated with inner membrane. Cytochrome c5 is the major electron donor to AniA. Reduced form cytochrome c5 is able to donate electrons to AniA at a physiologically relevant rate. In addition, the second haem domain of cytochrome c5 is the direct donor to AniA. It presents a potential problem for inter-electron transfer between c5 and AniA, which are associated with inner and outer membrane respectively. Trihaem CcoP is the alternative electron donor to AniA in N. gonorrhoeae. The 3rd haem domain of N. gonorrhoeae CcoP is able to donate electrons to AniA at a physiologically relevant rate, suggesting there is alternative route for nitrite reduction in N gonorrhoeae. N. elongata cytochrome is an electron donor to AniA. N. elongata cytochrome which has high degree of similarity with c5, is confirmed to donate electrons to AniA at a physiologically relevant rate, suggesting N. elongata has one other route for nitrite reduction. Laz is not involved in nitrite reduction. Laz is able to receive electrons from cytochrome c5 at physiological relevant rate, but cannot donate electrons to AniA. Based on laz mutagenesis study, laz mutant strain has limited affect on growth and nitrite usage compared to the wild type strain. Cytochrome cx is not involved in oxygen reduction. Cytochrome cx has presumably been found to be involved in oxygen reduction in N. meningitidis, but not in N. gonorrhoeae. N. meningitidis carrying an N. gonorrhoeae ccoP gene has a similar growth rate as the growth rate of the wild type strain and also cx mutant strains.