Affiliation:
1. Fermentation Research Department, Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065
Abstract
Ethionine supplementation of a defined medium for growth of
Pseudomonas denitrificans
inhibited vitamin B
12
overproduction and led to the elaboration of a red pigment. The pigment was shown to be coproporphyrin III. Inhibition by ethionine of cobalamin synthesis is probably due to interference of methylation of the corrin nucleus by methionine. Accumulation of coproporphyrin III is thought to result from interference by ethionine with the activity of methionine in the coproporphyrinogenase reaction; this would inhibit formation of heme, the feedback inhibitor and corepressor of δ-aminolevulinate synthetase, thus allowing unregulated synthesis of coproporphyrinogen III and its degradation product, coproporphyrin III. Betaine, known to be required for vitamin B12 overproduction, was found to be an essential requirement for porphyrin overproduction in the presence of ethionine. Low-level production of porphyrin, which occurs in the absence of ethionine, also required betaine supplementation. Betaine is thus required for overproduction of both corrins and porphyrins in
P. denitrificans
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
23 articles.
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