Recent work from our laboratory identified four structural genes, prpBCDE, involved in propionate catabolism in Salmonella typhimurium. The structural prp genes are organized into an operon and are thought to be responsible for the breakdown of propionate. We have isolated S. typhimurium strains that lack each prp structural gene to allow the accumulation of propionate catabolic intermediates. 13C NMR will be utilized on these S. typhimurium strains to identify the intermediates in this catabolic pathway. These strains will be grown in conditions to induce the synthesis of prp genes to allow uptake of 13C-propionate and labeling of the catabolic intermediate. Both broad-band decoupling and off-resonance CMR spectra of the labeled cell cultures will be obtained to identify the propionate catabolites. We expect the oxidation state of the C-1 (carboxylic function) to remain unchanged, however, labels at the C-2 and C-3 will be useful for distinguishing secondary alcohol or carbonyl functions. Cell-free extracts will be used to study specific steps of the catabolic pathway in vitro.
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