Composition and activity of the Rhodobacter capsulatus degradosome vary under different oxygen concentrations

The influence of changes in temperature or oxygen tension during growth of Rhodobacter capsulatus on the composition and activity of the degradosome, an RNA-processing protein complex, was investigated. Only minor differences in the amount of specific proteins of the complex were observed after a decrease or increase of the temperature, but dramatic variations were detectable during growth at different oxygen concentrations. In particular, the amount of the transcription factor Rho, which was previously shown to be associated with the R. capsulatus degradosome, was strongly increased under aerobic conditions. Remarkably, oxygen tension oppositely affected the levels of the two helicases associated with the degradosome. RNase E and the degradosome from aerobically grown cultures degraded a transcript which represents part of the puf operon encoding proteins of the photosynthetic apparatus faster than did the degradosome from semiaerobically grown cultures. Copyright (C) 2004 S. Karger AG, Basel.