ISHS Acta Horticulturae 273: V International Workshop on Fireblight
MECHANISM BY WHICH THE ANTIBIOTIC OF ERWINIA HERBICOLA Eh318 INHIBITS ERWINIA AMYLOVORA Ea273 |
| Authors: | R.S. Wodzinski, M.B. Mudgett, S.V. Beer |
| Abstract:
Antibiotic production is important in the mechanism by which some strains of E. herbicola inhibit E. amylovora. The antibiotic of Eh318, which inhibits Ea273, is not inhibitory to Ea273 in the presence of a combination of arginine and histidine; arginine has a much greater effect on reducing the toxicity of the antibiotic to Ea273 than does histidine. A crude preparation of the enzyme N-acetylornithine transaminase of Ea273, which converts N-acetylglutamyl semialdehyde to N-acetylornithine in arginine biosynthesis, is inhibited by the purified antibiotic of Eh318. Kinetic analysis with partially purified enzyme shows that the antibiotic of Eh318 is a competitive inhibitor of the enzyme when N-acetylornithine is the varied substrate. The transaminases of Eh318 and Ea273R318, a spontaneous mutant of Ea273 that is resistant to the antibiotic of Eh318, are both inhibited by the purified antibiotic. Thus, resistance to the antibiotic is not the result of altered (resistant) forms of the transaminase. | |
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