title: Derepression of GDP-alpha-mannose and UDP-glucose pyrophosphorylases by a regulator gene mutation; episomal dominance in partial diploids.
abstract: Mutants of Escherichia coli K12 at the capR locus are overproduce capsular polysaccharide, and are derepressed for synthesis of several enzymes involved in capsular polysaccharide synthesis(1-3) including GDP-mannose pyrophosphorylase.(8) UDP-glucose pyrophosphorylase is also derepressed in a haploid capR9 mucoid mutant. Heterozygous mucoid partial diploids with the capR9 allele on the episome and the wild-type (capR(+)) allele on the chromosome (F'capR9/capR(+)) are derepressed for UDP-glucose pyrophosphorylase and GDP-mannose pyrophosphorylase, while the reciprocal nonmucoid heterozygotes (F'capR(+)/capR9) are repressed for these enzymes. These results provide evidence that the episomal capR allele is dominant with respect to synthesis of these two enzymes.
mesh_terms: D004171:Diploidy; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology; D005799:Genes, Dominant; D005809:Genes, Regulator; D006238:Haploidy; D009154:Mutation; D009713:Nucleotidyltransferases / Q000096:biosynthesis*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis
chemical_list: D011135:Polysaccharides, Bacterial; D009713:Nucleotidyltransferases