title: Evolution of aromatic β-glucoside utilization by successive mutational steps in Escherichia coli.
abstract: The bglA gene of Escherichia coli encodes phospho-β-glucosidase A capable of hydrolyzing the plant-derived aromatic β-glucoside arbutin. We report that the sequential accumulation of mutations in bglA can confer the ability to hydrolyze the related aromatic β-glucosides esculin and salicin in two steps. In the first step, esculin hydrolysis is achieved through the acquisition of a four-nucleotide insertion within the promoter of the bglA gene, resulting in enhanced steady-state levels of the bglA transcript. In the second step, hydrolysis of salicin is achieved through the acquisition of a point mutation within the bglA structural gene close to the active site without the loss of the original catabolic activity against arbutin. These studies underscore the ability of microorganisms to evolve additional metabolic capabilities by mutational modification of preexisting genetic systems under selection pressure, thereby expanding their repertoire of utilizable substrates.
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.
authors.forename: Parisa
authors.initials: P
authors.lastname: Zangoui
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India.
authors.forename: Kartika
authors.initials: K
authors.lastname: Vashishtha
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, India mahi@mrdg.iisc.ernet.in.
authors.forename: Subramony
authors.initials: S
authors.lastname: Mahadevan
mesh_terms: D001483:Base Sequence; D001592:Benzyl Alcohols / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005960:Glucosides / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D001617:beta-Glucosidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D001592:Benzyl Alcohols; D029968:Escherichia coli Proteins; D005960:Glucosides; C005696:salicin; D001617:beta-Glucosidase