Affiliation:
1. School of Biosciences
2. School of Chemistry, Cardiff University, Cardiff CF10 3US, United Kingdom
Abstract
ABSTRACT
Sulfoquinovose (6-deoxy-6-sulfo-
d
-glucopyranose), formed by the hydrolysis of the plant sulfolipid, is a major component of the biological sulfur cycle. However, pathways for its catabolism are poorly delineated. We examined the hypothesis that mineralization of sulfoquinovose to inorganic sulfate is initiated by reactions of the glycolytic and/or Entner-Doudoroff pathways in bacteria. Metabolites of [U-
13
C]sulfoquinovose were identified by
13
C-nuclear magnetic resonance (NMR) in strains of
Klebsiella
and
Agrobacterium
previously isolated for their ability to utilize sulfoquinovose as a sole source of carbon and energy for growth, and cell extracts were analyzed for enzymes diagnostic for the respective pathways.
Klebsiella
sp. strain ABR11 grew rapidly on sulfoquinovose, with major accumulations of sulfopropandiol (2,3-dihydroxypropanesulfonate) but no detectable release of sulfate. Later, when sulfoquinovose was exhausted and growth was very slow, sulfopropandiol disappeared and inorganic sulfate and small amounts of sulfolactate (2-hydroxy-3-sulfopropionate) were formed. In
Agrobacterium
sp. strain ABR2, growth and sulfoquinovose disappearance were again coincident, though slower than that in
Klebsiella
sp. Release of sulfate was still late but was faster than that in
Klebsiella
sp., and no metabolites were detected by
13
C-NMR. Extracts of both strains grown on sulfoquinovose contained phosphofructokinase activities that remained unchanged when fructose 6-phosphate was replaced in the assay mixture with either glucose 6-phosphate or sulfoquinovose. The results were consistent with the operation of the Embden-Meyerhoff-Parnas (glycolysis) pathway for catabolism of sulfoquinovose. Extracts of
Klebsiella
but not
Agrobacterium
also contained an NAD
+
-dependent sulfoquinovose dehydrogenase activity, indicating that the Entner-Doudoroff pathway might also contribute to catabolism of sulfoquinovose.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
53 articles.
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