Regulation of nitrogenase synthesis by Klebsiella pneumoniae

Abstract

PARUKO, R. A., and P. W. WILSON. 1970. Regulation of nitrogenase synthesis by Klebsiellapr~e~irrroniae.Can. J. Microbial. 16: 681-685. The synthesis of the nitrogenase system in Nz-fixing bacteria is repressed when the organisms are grown on NH4+-N. It has not been unequivocally determined, however, if N2 is necessary for induction in NH4+-deficient cultures. Previous experiments with Klebsiella ptre~itr~ot~iae, Azotohacter vinelandii, Closrridium pasteuriatzllm, and Rl~odospirillvm r~rbrlim have been inconclusive owing to inadequacy of the methods, primarily the presence of Nz as a contaminant in the gases used. Results of experiments described in this paper using cultures of K. pnellmorziae M5al grown under both limited N2 and in its apparent absence indicate that the control of nitrogenase is most likely through simple repression by NH4+ o r by an incorporation product, e.g., glutamine.

Control of Nitrogenase Synthesis in Klebsiella pneumoniae

“…Ammonium ions stimulate cell-free amino acid incorporation (Lubin & Ennis, 1964) ; high NH$ concentrations are required for ribosomal stability in vitro (Hartman, Nolan & Amaya, 1971) and for the peptidyl transferase reaction (Miskin, Zamir & Elson, 1970). Under argon, only a limited amount of nitrogenase was derepressed, as previously observed by Parejko & Wilson, 1970; Casamino acids added prior to derepression increased the final activity obtained in one instance. Klebsiella pneumoniae, therefore, did not synthesize nitrogenase completely when only endogenous nitrogen sources were available.…”

“…These include glutamine in Klebsiella pneumoniae (Parejko & Wilson, 1970), aspargine (Wilson, Hull & Burris, 1943;St John & Brill, 1972), urea (Wilson et al 1943;Hardy & Knight, 1967) and nitrate (Wilson et al 1943;Drozd et al 1972) in Azotobacter. This diversity suggests that a common intermediate, the most obvious being NH,+, is the effector of repression.…”

“…This shorter lag could have arisen from the use of nitrogen-fixing organisms as inocula because the length of such a lag in Clostridium pasteurianum depended on the number of generations of growth on NH,+ (Daesch & Mortenson, 1972), a shorter lag ensuing where residual nitrogenase was present. Long pre-fixation lags recorded for K. pneumoniae may have arisen from depletion of amino acid pools (Yoch & Pengra, 1966;Parejko & Wilson, 1970). Yeast extract, peptone, Casamino acids and various single amino acids shortened this lag (Yoch & Pengra, 1966;Patil, Pengra & Yoch, 1967).…”

“…Yeast extract, peptone, Casamino acids and various single amino acids shortened this lag (Yoch & Pengra, 1966;Patil, Pengra & Yoch, 1967). Parejko & Wilson (1970) claimed that amino acids increased the nitrogenase content of a derepressed culture above that of one grown on N2 as sole nitrogen source. They also showed that was maintained at 20 O C in air on 2 % nutrient agar slopes and subcultured monthly.…”

Genetic Analysis of a Pleiotropic Mutant of Klebsiella pneumoniae Affected in Nitrogen Metabolism

“…Magasanik and his co-workers (Tyler et al, 1974) demonstrated, using a cell-free transcription system, that unadenylylated glutamine synthetase activates the expression of the histidine utilization genes. Glutamine synthetase was also postulated to play an important role in the control of the utilization of alternative nitrogen sources, including N2, that are subject to repression by NH4+ (Shanmugam & Valentine, 1975;Magasanik, 1976).In Klebsiella pneumoniae, glutamine and glutamate play an important role in controlling nitrogenase biosynthesis (Parejko & Wilson, 1970;Shanmugam & Morandi, 1976), but the precise biochemical nature of this control is still unknown. To understand this process, we have sought for and isolated a pleiotropic, thermosensitive mutant strain of K. pneumonide.…”