title: dpp genes of Rhizobium leguminosarum specify uptake of delta-aminolevulinic acid.
abstract: An operon with homology to the dppABCDF genes required to transport dipeptides in bacteria was identified in the N2-fixing symbiont, Rhizobium leguminosarum. As in other bacteria, dpp mutants were severely affected in the import of delta-aminolevulinic acid (ALA), a heme precursor. ALA uptake was antagonized by adding dipeptides, indicating that these two classes of molecule share the same transporter. Mutations in dppABCDF did not affect symbiotic N2 fixation on peas, suggesting that the ALA needed for heme synthesis is not supplied by the plant or that another uptake system functions in the bacteroids. The dppABCDF operon of R. leguminosarum resembles that in other bacteria, with a gap between dppA and dppB containing inverted repeats that may stabilize mRNA and may explain why transcription of dppA alone was higher than that of dppBCDF. The dppABCDF promoter was mapped and is most likely recognized by sigma70.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich, UK.
authors.forename: R A
authors.initials: RA
authors.lastname: Carter
authors.forename: K H
authors.initials: KH
authors.lastname: Yeoman
authors.forename: A
authors.initials: A
authors.lastname: Klein
authors.forename: A H F
authors.initials: AH
authors.lastname: Hosie
authors.forename: G
authors.initials: G
authors.lastname: Sawers
authors.forename: P S
authors.initials: PS
authors.lastname: Poole
authors.forename: A W B
authors.initials: AW
authors.lastname: Johnston
mesh_terms: D000622:Aminolevulinic Acid / Q000378:metabolism*; D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins; D004151:Dipeptides / Q000494:pharmacology; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005838:Genotype; D006418:Heme / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009876:Operon; D033902:Periplasmic Binding Proteins; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D016961:Rhizobium leguminosarum / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; C412423:DPPD protein, Mycobacterium tuberculosis; D004151:Dipeptides; D029968:Escherichia coli Proteins; D033902:Periplasmic Binding Proteins; D012333:RNA, Messenger; C066768:dppA protein, E coli; D006418:Heme; D000622:Aminolevulinic Acid