Metabolism of 35S-sulphate and properties of APS-kinase and PAPS-reductase in Nitrobacter agilis

Varma, Ajit; Nicholas, D. J. D.

doi:10.1007/bf00424867

Cited by 10 publications

(1 citation statement)

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“…3S04-accumulation in whole cells was measured after a 10-min incubation of a washed cell suspension (A^,= 8) in complete medium containing 68 ,uM Na23S04 Incorporation of so4 into cell protein was determined as follows: cells (1 ml) were derepressed for nitrogenase in the presence of 0.1 mM Na2SO4 ptus Na2,5S04 (30 lMuC); after derepression 0.9 ml was added to 5 ml of boiling ethanol, dried, suspended in 5) trichloroacetic acid, filtered through glass fiber, and counted. Adenosine-5'-phosphosulfate and 3'-phosphoadenosine-5'-phosphosulfate synthesis from 35S042was studied in crude extracts (26).…”

Section: Methodsmentioning

confidence: 99%

Biosynthesis of the iron-molybdenum cofactor and the molybdenum cofactor in Klebsiella pneumoniae: effect of sulfur source

Ugalde¹,

Imperial²,

Shah³

et al. 1985

J Bacteriol

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NifQand Molmutants of Klebsiella pneumoniae show an elevated molybdenum requirement for nitrogen fixation. Substitution of cystine for sulfate as the sulfur source in the medium reduced the molybdenum requirement of these mutants to levels required by the wild type. Cystine also increased the intracellular molybdenum accumulation of NifQand Molmutants. Cystine did not affect the molybdenum requirement or accumulation in wild-type K. pneumoniae. Sulfate transport and' metabolism in K. pneumoniae were repressed by cystine. However, the effect of cystine on the molybdenum requirement could not be explained by an interaction between sulfate and molybdate at the transport level. Cystine increased the molybdenum requirement of Molmutants for nitrate reductase activity by at least 100-fold. Cystine had the samne effect on the molybdenum requirement for nitrate reductase activity in Escherichia coli Ch1D-mutants. This shows that cystine does not have a generalized effect on molybdenum metabolism. Millimolar concentrations of molibdate inhibited nitrogenase and nitrate reductase derepression with sulfate as the sulfur source, but not with cystine. The inhibition was the result of a specific antagonism of sulfate metabolism by molybdate. The effects of nifQ and mol mutations on nitrogenase could be suppressed either by the addition of cystine or by high

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Section: Methodsmentioning

confidence: 99%