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Physiology and Biochemistry

The Relation Between Glucose Repression of Endo-Polygalacturonate Trans-Eliminase and Adenosine 35-Cyclic Monophosphate Levels in Erwinia carotovora. J. P. Hubbard, Graduate Research Assistant, Department of Plant Pathology, University of Massachusetts, Amherst, MA 01003; J. D. Williams(2), R. M. Niles(3), and M. S. Mount(4). (2)Graduate Research Assistant, Department of Plant Pathology, University of Massachusetts, Amherst, MA 01003; (3)Assistant Professor, Department of Biochemistry, Boston University Medical School, Boston, MA 02118; (4)Associate Professor, Department of Plant Pathology, University of Massachusetts, Amherst, MA 01003. Phytopathology 68:95-99. Accepted for publication 8 July 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-95.

The level of intracellular endo-polygalacturonate trans-eliminase (PGTE) activity by Erwinia carotovora on minimal salts medium was affected by the available carbon source. When cells growing on sodium polypectate were supplemented with glucose, the level of intracellular PGTE activity decreased. Exogenously supplied adenosine 3,5-cyclic monophosphate (cAMP) reversed repression of intracellular PGTE activity if the substrate of the enzyme, sodium polypectate, was present. Various analogues of cAMP and other nucleotide derivatives failed to reverse glucose repression of PGTE activity. Measurements of cAMP demonstrated that a decrease in cAMP could be correlated with glucose repression of PGTE activity. As the PGTE activity increased in induced cultures, the specific concentration of cAMP increased.

Additional keywords: catabolite repression.