Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A crude Azotobacter nitrogenase complex contained a highly active adenylate kinase which caused rapid equilibration of AMP, ADP, and ATP. Purified molybdenum-iron protein preparations also contained measurable adenylate kinase activity which could be removed by adsorption and elution from hydroxylapatite. Independent of adenylate kinase, the highly purified molybdenum-iron protein from both Klebsiella pneumoniae and Azotobacter chroococcum catalyzed the exchange of [32P]orthophosphate with the terminal phosphate of ATP or ADP. The exchange labeling of ATP was stimulated by ferricyanide ion due to the inhibition of ATP hydrolysis linked to substrate reductions which cannot occur in the absence of reductant. This exchange reaction is responsible for reported ATP synthesis by crude nitrogenase preparations. Binding of ATP labeled with 32P in the terminal phosphate group was measured directly with concentrated solutions of the molybdenum-iron nitrogenase protein from K. pneumoniae by the column gel filtration method. The protein was saturated with ATP at a calculated ratio of 4.0 +/- 0.3 mol ATP/mol protein; half-saturation of 220 microM protein occurred at 600 +/- 100 microM. The interactions between adenine nucleotides and the molybdenum-iron protein suggest the involvement of the nucleotides in a role distinct from the established reactions with the iron protein of the nitrogenase complex. A dual role for ATP in the reduction of dinitrogen by isolated nitrogenase proteins would be consistent with the existence of binding sites for ATP on both the iron and molybdenum-iron proteins.
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PMID:Catalysis of exchange of terminal phosphate groups of ATP and ADP by purified nitrogenase proteins. 700 7

Proteinase treatment with chymotrypsin has been used to probe the structure of native Klebsiella pneumoniae nitrogenase MoFe protein (Kp1). Reaction with chymotrypsin did not bleach Kp1, suggesting that it did not destroy the metal centres, and the Mo and Fe contents of Kp1 were unchanged. High ratios of chymotrypsin to Kp1 (1:1 by mass) cleaved the beta-chain of Kp1 to give 44 and 14 kDa polypeptides, which N-terminal amino acid sequence analysis showed to be derived from cleavage at residue beta-Phe124. A mutant MoFe protein, Kp1Met-124, in which beta-Phe124 is replaced by methionine, was not cleaved by chymotrypsin. Under non-denaturing conditions, the 'nicked' beta-chain of the wild-type protein remained associated with the alpha-chain. The alpha-chain was not cleaved by the proteinase treatment. Fission of the wild-type beta-chain was accompanied by loss of enzyme activity, loss of intensity of the g = 3.7 e.p.r. signal derived from dithionite-reduced FeMoco and by changes in the visible spectrum. The e.p.r. spectra of potassium ferricyanide-oxidized native and digested Kp1 show differences in the signals between g = 1.6 and 2.0. After prolonged treatment, the final specific activity of Kp1 was about 25 +/- 5% of the initial activity. This corresponded to 25 +/- 5% of the beta-chain which was resistant to proteolytic action. Brief treatment of Kp1 with a lower concentration of chymotrypsin (chymotrypsin/Kp1 ratio = 1:10 by mass, for 10 min) preferentially cleaved high-molecular-mass polypeptides that routinely contaminate preparations of Kp1 prepared by standard procedures. Treatment with chymotrypsin followed by gel filtration to remove the proteinase and cleaved protein fragments can therefore be used to increase significantly the specific activity of Kp1 preparations and remove contaminating activities, such as the ATPase activity of myokinase.
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PMID:Klebsiella pneumoniae nitrogenase MoFe protein: chymotryptic proteolysis affects function by limited cleavage of the beta-chain and provides high-specific-activity MoFe protein. 838 37

The influence of cadmium on stress protein production in Escherichia coli K-12 (strain MG1655) was analysed using two-dimensional polyacrylamide gel electrophoresis and the gene-protein database of E. coli K-12. Cadmium (273 microM) caused complete but transient inhibition of growth accompanied by the synthesis of cadmium-induced proteins (CDPs). It was found that some CDPs induced during the growth-arrested phase belong to the heat-shock, oxidation stress, SOS and stringent response regulons, while others are general stress inducible proteins (e.g. H-NS, UspA). In addition, trigger factor, adenylate kinase, W-protein, the cold shock protein G041.2, and seven unknown proteins whose synthesis is not known to be controlled by a global regulator, were identified as immediate responders to cadmium exposure. The rate of synthesis of most of the immediate responders to cadmium exposure decreased when the growth of the cells resumed. However, seven CDPs, including those encoded by argI, tyrA and xthA, maintained a high production rate during growth in the presence of cadmium. Two of the unidentified proteins were N-terminally sequenced by Edman degradation. The N-terminal amino acid sequence of one of these proteins (designated F023.3) matches the E. coli open reading frame o216. This ORF is similar to the N-terminal third of the copper-binding protein amine oxidases (encoded by maoA) of both E. coli and Klebsiella pneumoniae (K. aerogenes). The other N-terminally sequenced protein (designated C044.6) matches perfectly the product of the metK gene, S-adenosylmethionine synthetase I. In comparison to untreated cells, cadmium-stressed cells were found to recover more rapidly during subsequent stress conditions, such as ethanol, osmotic, heat shock, and nalidixic acid treatment. The role of the CDPs is discussed in view of their physiological assignments in the cell.
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PMID:The cadmium-stress stimulon of Escherichia coli K-12. 957 78