title: Structural and functional analysis of the riboflavin synthesis genes encoding GTP cyclohydrolase II (ribA), DHBP synthase (ribBA), riboflavin synthase (ribC), and riboflavin deaminase/reductase (ribD) from Helicobacter pylori strain P1.
abstract: The functions of the riboflavin synthesis gene homologues ribA, ribBA, ribC, and ribD from Helicobacter pylori strain P1 were confirmed by complementation of defined Escherichia coli mutant strains. The H. pylori ribBA gene, which is similar to bifunctional ribBA genes of Gram-positive bacteria, fully complemented the ribB mutation and partially restored growth in a ribC mutant. However, ribBA did not complement the ribA mutation in E. coli, thus explaining the presence of the additional separate copy of the ribA gene in the H. pylori chromosome. In E. coli exclusively ribA conferred hemolytic activity and gave rise to production of molecules with fluorescence characteristics similar to flavins, as observed earlier. The E. coli hemolysin ClyA was not involved in causing the hemolytic phenotype. No riboflavin synthesis genes on plasmids conferred iron uptake functions to a siderophore-deficient mutant of E. coli. Marker exchange mutagenesis of the genes in H. pylori was not successful indicating that riboflavin synthesis is essential for basic metabolic functions of the gastric pathogen.
authors.affiliation: University of Freiburg, Institute of Medical Microbiology and Hygiene, Department of Microbiology, Freiburg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Fassbinder
authors.forename: M
authors.initials: M
authors.lastname: Kist
authors.forename: S
authors.initials: S
authors.lastname: Bereswill
mesh_terms: D000619:Aminohydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005453:Fluorescence; D006136:GTP Cyclohydrolase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016480:Helicobacter pylori / Q000201:enzymology / Q000235:genetics*; D006461:Hemolysis; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D012256:Riboflavin / Q000096:biosynthesis*; D012258:Riboflavin Synthase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013403:Sugar Phosphates / Q000378:metabolism; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D013403:Sugar Phosphates; C066494:3,4-dihydroxy-2-butanone-4-phosphate; D007501:Iron; D012258:Riboflavin Synthase; D000619:Aminohydrolases; C022531:riboflavin deaminase; D006136:GTP Cyclohydrolase; C111303:RibBA protein, Helicobacter pylori; D012256:Riboflavin