Metabolic Control of Klebsiella pneumoniae mRNA Degradation by the Availability of Fixed Nitrogen

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Abstract
SUMMARY: The chemical and functional stability of Klebsiella pneumoniae mRNAs was dependent on the nitrogen status of the organism. During exponential growth on N2 or NH4 + as N-source the half-lives of mRNAs were 10 and 4 min, respectively. When NH4 +-grown cells were starved of NH4 + for 3 h, under which conditions the nitrogen fixation (nif) genes were derepressed, the half-life of mRNAs increased to 20 min. Addition of NH4 + to such N-starved suspensions rapidly destabilized mRNAs with a resultant half-life of 9 min. This destabilization occurred even in the presence of transcription inhibitors, which indicated metabolic control of mRNA degradation. Under most conditions studied the functional decay of nif-specific mRNAs paralleled the decay of bulk mRNAs.