title: The naringenin-induced exoproteome of Rhizobium etli CE3.
abstract: Flavonoids excreted by legume roots induce the expression of symbiotically essential nodulation (nod) genes in rhizobia, as well as that of specific protein export systems. In the bean microsymbiont Rhizobium etli CE3, nod genes are induced by the flavonoid naringenin. In this study, we identified 693 proteins in the exoproteome of strain CE3 grown in minimal medium with or without naringenin, with 101 and 100 exoproteins being exclusive to these conditions, respectively. Four hundred ninety-two (71%) of the extracellular proteins were found in both cultures. Of the total exoproteins identified, nearly 35% were also present in the intracellular proteome of R. etli bacteroids, 27% had N-terminal signal sequences and a significant number had previously demonstrated or possible novel roles in symbiosis, including bacterial cell surface modification, adhesins, proteins classified as MAMPs (microbe-associated molecular patterns), such as flagellin and EF-Tu, and several normally cytoplasmic proteins as Ndk and glycolytic enzymes, which are known to have extracellular "moonlighting" roles in bacteria that interact with eukaryotic cells. It is noteworthy that the transmembrane ß (1,2) glucan biosynthesis protein NdvB, an essential symbiotic protein in rhizobia, was found in the R. etli naringenin-induced exoproteome. In addition, potential binding sites for two nod-gene transcriptional regulators (NodD) occurred somewhat more frequently in the promoters of genes encoding naringenin-induced exoproteins in comparison to those ofexoproteins found in the control condition.
authors.affiliation: Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Morelos, Mexico.|Mass Spectrometry and Proteomics Laboratory, Department of Clinical Research, University of Bern, 3010, Bern, Switzerland.|Faculty of Science, Department of Chemistry and Biochemistry, University of Bern, 3010, Bern, Switzerland.
authors.forename: Niurka
authors.initials: N
authors.lastname: Meneses
authors.affiliation: Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Morelos, Mexico.
authors.forename: Hermenegildo
authors.initials: H
authors.lastname: Taboada
authors.affiliation: Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Morelos, Mexico.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Dunn
authors.affiliation: Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Morelos, Mexico.
authors.forename: María Del Carmen
authors.initials: MDC
authors.lastname: Vargas
authors.affiliation: Mass Spectrometry and Proteomics Laboratory, Department of Clinical Research, University of Bern, 3010, Bern, Switzerland.
authors.forename: Natasha
authors.initials: N
authors.lastname: Buchs
authors.affiliation: Mass Spectrometry and Proteomics Laboratory, Department of Clinical Research, University of Bern, 3010, Bern, Switzerland.
authors.forename: Manfred
authors.initials: M
authors.lastname: Heller
authors.affiliation: Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, 62210, Cuernavaca, Morelos, Mexico. encarnac@ccg.unam.mx.
authors.forename: Sergio
authors.identifier: http://orcid.org/0000-0001-7889-1681
authors.initials: S
authors.lastname: Encarnación
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D007887:Fabaceae / Q000382:microbiology; D044950:Flavanones / Q000494:pharmacology*; D005786:Gene Expression Regulation; D009586:Nitrogen Fixation / Q000235:genetics; D055170:Plant Root Nodulation / Q000235:genetics*; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D042163:Rhizobium etli / Q000235:genetics* / Q000378:metabolism*; D013559:Symbiosis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D044950:Flavanones; D020543:Proteome; C005273:naringenin
keywords: Naringenin; Nitrogen Fixation; Proteomics; Rhizobium