Cobalamin-dependent 1,2-propanediol utilization by Salmonella typhimurium

Abstract

The enteric bacterium Salmonella typhimurium utilizes 1,2-propanediol as a sole carbon and energy source during aerobic growth, but only when the cells are also provided with cobalamin as a nutritional supplement. This metabolism is mediated by the cobalamin-dependent propanediol dehydratase enzyme pathway. Thirty-three insertion mutants were isolated that lacked the ability to utilize propanediol, but retained the ability to degrade propionate. This phenotype is consistent with specific blocks in one or more steps of the propanediol dehydratase pathway. Enzyme assays confirmed that propanediol dehydratase activity was absent in Same of the mutants. Thus, the affected genes were designated pdu (for defects in propanediol utilization). Seventeen mutants carried pdu: :lac operon fusions, and these fusions were induced by propanediol in the culture medium. All of the pdu

Short N-terminal sequences package proteins into bacterial microcompartments

“…Salmonella enterica produces an MCP used for B 12 -dependent 1,2-propanediol (1,2-PD) utilization (Pdu MCP) (19,20). 1,2-PD is a major product of the anaerobic degradation of the plant sugars rhamnose and fucose and is an important carbon and energy source in natural environments (21,22).…”

The control region of the pdu/cob regulon in Salmonella typhimurium

“…Queuosine synthetase reduces epoxyqueuosine to queuosine, a modified base found in four tRNAs (17). Propanediol dehydratase rearranges 1,2-propanediol to yield propionaldehyde and H20 (18,38).…”

Biochemical evidence that the pduS gene encodes a bifunctional cobalamin reductase

“…Salmonella enterica degrades 1,2-propanediol (1,2-PD) in a coenzyme B 12 (adenosylcobalamin; AdoCbl)-dependent fashion (Jeter, 1990). 1,2-PD is a major product of the fermentation of the common plant sugars rhamnose and fucose and is thought to be an important carbon source in anaerobic environments such as the large intestines of higher animals (Obradors et al, 1988;Toraya et al, 1980).…”

“…In S. enterica, the genes specifically involved in 1,2-PD utilization (pdu) are found in a single, large, contiguous cluster, the pdu locus (Bobik et al, 1999;Jeter, 1990). Included are the pocR and pduF genes (which encode a positive transcriptional regulator and a 1,2-PD diffusion facilitator, respectively) (Bobik et al, 1992;Chen et al, 1995) as well as the adjacent, but divergently transcribed, pdu operon, which includes 21 additional genes (Bobik et al, 1999;Jeter, 1990).…”

“…In S. enterica, the genes specifically involved in 1,2-PD utilization (pdu) are found in a single, large, contiguous cluster, the pdu locus (Bobik et al, 1999;Jeter, 1990). Included are the pocR and pduF genes (which encode a positive transcriptional regulator and a 1,2-PD diffusion facilitator, respectively) (Bobik et al, 1992;Chen et al, 1995) as well as the adjacent, but divergently transcribed, pdu operon, which includes 21 additional genes (Bobik et al, 1999;Jeter, 1990). Of these 21 genes, six encode enzymes of the 1,2-PD degradative pathway (pduCDEPQW) (Bobik et al, 1997(Bobik et al, , 1999Leal et al, 2003a) and seven are thought to encode structural proteins required for polyhedral body formation (pduABJKNTU) (Bobik et al, 1999;Havemann et al, 2002;Havemann & Bobik, 2003).…”