Expression of the PII-AmtB encoding operons in Rhodospirillum rubrum and studies of the functional role(s) of GlnB, GlnJ and AmtB1 in nitrogen metabolism
(English)Manuscript (preprint) (Other academic)
In Rhodospirillum rubrum and many other diazotrophs, PII proteins and the ammonium transport protein AmtB have been shown to play central roles in the regulation of nitrogen metabolism. In this report we have used Real-time RT-PCR to study the transcription of the genes encoding three PII proteins and the AmtB proteins in R. rubrum. We have generated amtB1 and amtB2 mutants and in the amtB1 mutant strains ammonium nitrogenase switch-off is lost although the rate of ammonium uptake is not affected compared to wild type. In contrast darkness switch-off is unaffected. Most interestingly, we also show that the uridylylation status of GlnB is different from that of GlnJ under certain conditions in the amtB1 mutant strain, which is the first demonstration of physiological selectivity in PII modification in vivo, supporting the proposed different functions for these paralogs in the cell. We suggest that the primary role of AmtB1 in this diazotroph, is as a central component together with GlnJ in signal transduction regulating nitrogen metabolism.
Research subject Biochemistry
IdentifiersURN: urn:nbn:se:su:diva-30812OAI: oai:DiVA.org:su-30812DiVA: diva2:274155