title: Diminished redundancy of outer membrane factor proteins in rhizobiales: a nodT homolog is essential for free-living Rhizobium etli.
abstract: Rhizobium etli is a gram-negative soil bacterium that induces nitrogen-fixing nodules on common bean roots (Phaseolus vulgaris). R. etli encodes two genes homologous to nodT of Rhizobium leguminosarum. nodTch is chromosomal and forms an operon with new genes resembling a multi-drug efflux pump of the resistance-nodulation-cell division (RND) family. nodTch is the last gene of this operon and can also be independently transcribed; the gene product is located in the bacterial outer membrane. Cell survival requires nodTch under all conditions tested. A second nodT gene, nodTpc, is encoded by plasmid c; it is constitutively transcribed but does not complement the essential function encoded by nodTch. NodT proteins belong to the outer membrane efflux proteins of the TolC superfamily. The number of duplications in the tolC gene family positively correlates with genome size in gram-negative bacteria. Nonetheless, some alpha-proteobacteria, including R. etli, encode fewer outer membrane factor exporters than expected suggesting further roles in addition to detoxification.
authors: Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
authors: Armando
authors: A
authors: Hernández-Mendoza
authors: Noreide
authors: N
authors: Nava
authors: Olivia
authors: O
authors: Santana
authors: Cei
authors: C
authors: Abreu-Goodger
authors: Anibal
authors: A
authors: Tovar
authors: Carmen
authors: C
authors: Quinto
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002876:Chromosomes, Bacterial; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D010957:Plasmids / Q000235:genetics; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D042163:Rhizobium etli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C064151:nodT protein, Rhizobium leguminosarum