IDENTIFICATION OF SYMBIOSIS-SPECIFIC C-TYPE CYTOCHROMES AND A PUTATIVE OXIDASE IN BACTEROIDS OF RHIZOBIUM-LEGUMINOSARUM BIOVAR VICIAE

Covalently bound haem proteins and cytochromes were analysed in Rhizob ium leguminosarum biovar viciae free-living cells and nitrogen-fixing bacteroids isolated from pea nodules. Increased levels of spectroscopi cally detectable cytochrome c in bacteroids were correlated with the a ppearance of two proteins of M(r) 30 000 and 28 000 that contained cov alently bound haem. Conversely, bacteroids had undetectable levels of a periplasmic cytochrome c of M(r) 14 000 that is normally present in free-living bacteria. Difference spectra confirmed that the terminal o xidases, cytochromes aa(3) and d(1) were absent, and photodissociation spectra revealed novel components that may be due to a bacteroid term inal oxidase.