Regulation of Glutamine Synthetase II. Patterns of Feedback Inhibition in Microorganisms1
AUTOR(ES)
Hubbard, Jerry S.
RESUMO
The feedback inhibition of glutamine synthetase was investigated by use of partially purified enzyme preparations from Salmonella typhimurium, Micrococcus sodonensis, Pseudomonas fluorescens, Bacillus cereus, Bacillus licheniformis, Clostridium pasteurianum, Rhodospirillum rubrum, Neurospora crassa, Candida utilis, and Chlorella pyrenoidosa. Inhibition analyses indicated that the enzyme of each organism can be effectively regulated with mixtures of end products from the diverse pathways of glutamine metabolism. When tested individually, tryptophan, histidine, alanine, glycine, glutamine, 5′-adenylate (AMP), cytidine-5′-triphosphate, carbamyl phosphate, and glucosamine-6-phosphate gave limited inhibition. In most cases, the inhibitors were independent in their action, and cumulative degrees of inhibition were obtained with mixtures of these end products. In contrast, with the glutamine synthetases of the two Bacillus species, the simultaneous presence of AMP and histidine (or AMP and glutamine) gave inhibition greater than the sum of the amounts of inhibition caused by either inhibitor alone. Also, alanine and carbamyl phosphate acted synergistically to inhibit the enzyme from N. crassa. The remarkable similarity in the overall patterns of end-product inhibition observed with the enzymes from different sources indicates that these diverse organisms have evolved comparable mechanisms for the regulation of glutamine metabolism. Nevertheless, the enzymes from different sources do differ significantly in their physical and catalytic properties, as was demonstrated by dissimilarities in their purification behaviors, specificity for nucleotide substrate, ability to catalyze the glutamyl transfer reaction, and ability to utilize Mn++ and Mg++ as activators for the biosynthetic reaction.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=276552Documentos Relacionados
- TERMINAL RESPIRATORY PATTERNS IN MICROORGANISMS1
- Regulation of Glutamine Synthetase X. Effect of Growth Conditions on the Susceptibility of Escherichia coli Glutamine Synthetase to Feedback Inhibition
- Preservation of Microorganisms by Freeze-drying: II. The Destructive Action of Oxygen. Additional Stabilizers for Serratia marcescens. Experiments with Other Microorganisms1
- MICROBIAL THERMOGENESIS II. HEAT PRODUCTION IN MOIST ORGANIC MATERIALS WITH SPECIAL REFERENCE TO THE PART PLAYED BY MICROÖRGANISMS1
- Feedback inhibition of fully unadenylylated glutamine synthetase from Salmonella typhimurium by glycine, alanine, and serine.