Affiliation:
1. Department of Microbiology, University of Mississippi School of Medicine, Jackson, Mississippi 39216
Abstract
Excretion of the metal-chelating phenolic acid, 2,3-dihydroxybenzoate, by a tryptophan-requiring strain (M-13) of
Bacillus subtilis
was inversely proportional to the iron added to the medium. Addition of iron as the ferric chelates of two secondary hydroxamates (ferri-schizokinen and Desferal) markedly reduced excretion. Synthesis of 2,3-dihydroxybenzoate from chorismate by extracts of
B. subtilis
M-13, grown in low-iron medium, was unaltered by additions of FeSO
4
, FeCl
3
, ferrischizokinen, 2,3-dihydroxybenzoate, the 2,3-dihydroxybenzoate-iron complex, or by extracts of cells grown in high-iron medium (which contained no demonstrable 2,3-dihydroxybenzoate-synthesizing activity) to the extracts of “low-iron cells.” Iron control seemed to involve repression of synthesis of the enzymes in the 2,3-dihydroxybenzoate pathway. Both ferri-schizokinen and 2,3-dihydroxybenzoate plus iron enhanced considerably the otherwise minimal repressive effects of iron at low concentrations. Ferri-schizokinen delayed derepression of the pathway in
B. subtilis
M-13, and reduced its rate of synthesis after derepression. Addition of FeSO
4
to derepressed cells of
B. subtilis
M-13 halted synthesis of the enzymes after a lag period. The effect of the ferric hydroxamates was related to the capacity of
B. subtilis
M-13 to incorporate
59
Fe
3+
from Desferal-
59
Fe
3+
. Cellular accumulation of
59
Fe
3+
from Desferal-
59
Fe
3+
after 20 min was nearly double that incorporated from
59
FeCl
3
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
26 articles.
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