title: Importance of facilitated diffusion for effective utilization of glycerol by Escherichia coli.
abstract: Wild-type Escherichia coli possesses an inducible permeation system which catalyzes facilitated diffusion of glycerol into the cell. A spectrophotometric method can be used to assess the presence of this mechanism. The structural gene for the facilitator (glpF) and the structural gene for glycerol kinase (glpK) apparently belong to a single operon. The glpF(+) allele permits effective glycerol utilization by the cells, and, at millimolar concentrations of glycerol, cells carrying the glpF(+) allele grow much faster than glpF genotypes. Although the glycerol-scavenging power of the cell depends both on the facilitated entry of the substrate and its subsequent trapping by an adenosine triphosphate-dependent phosphorylation, the two gene products, the facilitator and kinase, function independently. Wild-type Shigella flexneri appears to be glpK(+) but glpF. This organism grows slowly in media at low concentrations of glycerol. When the glpF(+) and glpK(+) alleles of E. coli are inserted into the S. flexneri genome by transduction, the hybrid strain grows rapidly in low glycerol medium. Vice versa, when the glpF and glpK(+) alleles of S. flexneri are incorporated into E. coli, the hybrid strain grows slowly in low glycerol medium.
mesh_terms: D000483:Alleles; D002247:Carbon Isotopes; D002463:Cell Membrane Permeability; D002474:Cell-Free System; D002874:Chromosome Mapping; D003470:Culture Media; D004058:Diffusion; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D005796:Genes; D008040:Genetic Linkage; D005990:Glycerol / Q000378:metabolism*; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D006822:Hybrid Cells; D009154:Mutation; D009604:Nitrosoguanidines; D009876:Operon; D010770:Phosphotransferases / Q000378:metabolism; D012763:Shigella flexneri / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D013053:Spectrophotometry; D014161:Transduction, Genetic
chemical_list: D002247:Carbon Isotopes; D003470:Culture Media; D009604:Nitrosoguanidines; D005993:Glycerolphosphate Dehydrogenase; D010770:Phosphotransferases; D005990:Glycerol