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Pyruvate metabolism and the phosphorylation state of isocitrate dehydrogenase in Escherichia coli.
J Gen Microbiol. 1986 Mar; 132(3):797-806.JG

Abstract

During growth of Escherichia coli on acetate, isocitrate dehydrogenase (ICDH) is partially inactivated by phosphorylation and is thus rendered rate-limiting in the Krebs cycle so that the intracellular concentration of isocitrate rises which, in turn, permits an increased flux of carbon through the anaplerotic sequence of the glyoxylate bypass. A large number of metabolites stimulate ICDH phosphatase and inhibit ICDH kinase in the wild-type (E. coli ML308) and thus regulate the utilization of isocitrate by the two competing enzymes, ICDH and isocitrate lyase. Addition of pyruvate to acetate grown cultures triggers a rapid dephosphorylation and threefold activation of ICDH, both in the wild-type (ML308) and in mutants lacking pyruvate dehydrogenase (ML308/Pdh-), PEP synthase (ML308/Pps-) or both enzymes (ML308/Pdh-Pps-). Pyruvate stimulates the growth on acetate of those strains with an active PEP synthase but inhibits the growth of those strains that lack this enzyme. When pyruvate is exhausted, ICDH is again inactivated and the growth rate reverts to that characteristic of growth on acetate. Because pyruvate stimulates dephosphorylation of ICDH in strains with differing capabilities for pyruvate metabolism, it seems likely that pyruvate itself is a sufficient signal to activate the dephosphorylation mechanism, but this does not discount the importance of other signals under other circumstances.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

3525743

Citation

el-Mansi, E M., et al. "Pyruvate Metabolism and the Phosphorylation State of Isocitrate Dehydrogenase in Escherichia Coli." Journal of General Microbiology, vol. 132, no. 3, 1986, pp. 797-806.
el-Mansi EM, Nimmo HG, Holms WH. Pyruvate metabolism and the phosphorylation state of isocitrate dehydrogenase in Escherichia coli. J Gen Microbiol. 1986;132(3):797-806.
el-Mansi, E. M., Nimmo, H. G., & Holms, W. H. (1986). Pyruvate metabolism and the phosphorylation state of isocitrate dehydrogenase in Escherichia coli. Journal of General Microbiology, 132(3), 797-806.
el-Mansi EM, Nimmo HG, Holms WH. Pyruvate Metabolism and the Phosphorylation State of Isocitrate Dehydrogenase in Escherichia Coli. J Gen Microbiol. 1986;132(3):797-806. PubMed PMID: 3525743.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Pyruvate metabolism and the phosphorylation state of isocitrate dehydrogenase in Escherichia coli. AU - el-Mansi,E M, AU - Nimmo,H G, AU - Holms,W H, PY - 1986/3/1/pubmed PY - 1986/3/1/medline PY - 1986/3/1/entrez SP - 797 EP - 806 JF - Journal of general microbiology JO - J Gen Microbiol VL - 132 IS - 3 N2 - During growth of Escherichia coli on acetate, isocitrate dehydrogenase (ICDH) is partially inactivated by phosphorylation and is thus rendered rate-limiting in the Krebs cycle so that the intracellular concentration of isocitrate rises which, in turn, permits an increased flux of carbon through the anaplerotic sequence of the glyoxylate bypass. A large number of metabolites stimulate ICDH phosphatase and inhibit ICDH kinase in the wild-type (E. coli ML308) and thus regulate the utilization of isocitrate by the two competing enzymes, ICDH and isocitrate lyase. Addition of pyruvate to acetate grown cultures triggers a rapid dephosphorylation and threefold activation of ICDH, both in the wild-type (ML308) and in mutants lacking pyruvate dehydrogenase (ML308/Pdh-), PEP synthase (ML308/Pps-) or both enzymes (ML308/Pdh-Pps-). Pyruvate stimulates the growth on acetate of those strains with an active PEP synthase but inhibits the growth of those strains that lack this enzyme. When pyruvate is exhausted, ICDH is again inactivated and the growth rate reverts to that characteristic of growth on acetate. Because pyruvate stimulates dephosphorylation of ICDH in strains with differing capabilities for pyruvate metabolism, it seems likely that pyruvate itself is a sufficient signal to activate the dephosphorylation mechanism, but this does not discount the importance of other signals under other circumstances. SN - 0022-1287 UR - https://www.unboundmedicine.com/medline/citation/3525743/Pyruvate_metabolism_and_the_phosphorylation_state_of_isocitrate_dehydrogenase_in_Escherichia_coli_ DB - PRIME DP - Unbound Medicine ER -