Laura Rubio-sanz - Academia.edu (original) (raw)

Uploads

Papers by Laura Rubio-sanz

Research paper thumbnail of DmeRF system is required for nickel and cobalt resistance in Rhizobium leguminosarum bv. viciae

A Cation Diffusion Facilitator (CDF) family with high sequence identity to DmeF (Divalent Metal E... more A Cation Diffusion Facilitator (CDF) family with high sequence identity to DmeF (Divalent Metal Efflux) from Cupridavirus metallidurans was identified in Rhizobium leguminosarum bv. viciae UPM1137. The R.leguminosarum dmeF mutant strain was highly sensitive to Co2+ and moderately to Ni2+, but not to other metals like Zn2+, Cu2+ or Mn2+. Also, an open reading frame located downstream of DmeF in R.leguminosarum, designatged DmeR, encoding a protein homologous to the nickel and cobalt regulator RcnR from E.coli. Our R.leguminosarum SPF25 DmeRF mutant exhibited also a reduced sensitive in cobalt and nickel.

Research paper thumbnail of Metal Transport in the Rhizobium-Legume Symbiosis

Ecology and Applications, 2013

Research paper thumbnail of Fluorescence and Molecular Mechanics of 1-Methyl Naphthalenecarboxylate/Cyclodextrin Complexes in Aqueous Medium

Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007

Steady-state, time-resolved fluorescence and Molecular Mechanics techniques have been used to stu... more Steady-state, time-resolved fluorescence and Molecular Mechanics techniques have been used to study the complexation of 1-methyl naphthalenecarboxylate with three naturally occurring cyclodextrins (CDs). Emission spectra of 1MN show two overlapping electronic bands. The stoichiometry, the formation constants of the complexes and the thermodynamics parameters upon inclusion were obtained from the change of intensity ratios R of the maxima of both bands and AEsae with [CD] and temperature. As with the 2-methyl naphthalenecarboxylate (2MN) guest, 1:1 stoichiometries were obtained for all complexes. The formation constants, however, were relatively low compared to those obtained for 2MN. Geometry of the complexes from Molecular Mechanics in the presence of water agrees with the experimental stoichiometry of the complexes and the signs of enthalpy and entropy changes. Quenching, R at [CD] fi ¥ and fluorescence depolarization measurements also support the proposed structures. As with 2MN the inclusion is mostly dominated by van der Waals interactions.

Research paper thumbnail of Functional and Expression Analysis of the Metal-Inducible dmeRF System from Rhizobium leguminosarum bv. viciae

Applied and Environmental Microbiology, 2013

A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metal... more A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel-and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria.

Research paper thumbnail of Conservation of Endangered Lupinus mariae-josephae in Its Natural Habitat by Inoculation with Selected, Native Bradyrhizobium Strains

Lupinus mariae-josephae is a recently discovered endemism that is only found in alkaline-limed so... more Lupinus mariae-josephae is a recently discovered endemism that is only found in alkaline-limed soils, a unique habitat for lupines, from a small area in Valencia region (Spain). In these soils, L. mariae-josephae grows in just a few defined patches, and previous conservation efforts directed towards controlled plant reproduction have been unsuccessful. We have previously shown that L. mariae-josephae plants establish a specific root nodule symbiosis with bradyrhizobia present in those soils, and we reasoned that the paucity of these bacteria in soils might contribute to the lack of success in reproducing plants for conservation purposes. Greenhouse experiments using L. mariae-josephae trap-plants showed the absence or near absence of L. mariae-josephae-nodulating bacteria in ''terra rossa'' soils of Valencia outside of L. mariaejosephae plant patches, and in other ''terra rossa'' or alkaline red soils of the Iberian Peninsula and Balearic Islands outside of the Valencia L. mariae-josephae endemism region. Among the bradyrhizobia able to establish an efficient symbiosis with L. mariae-josephae plants, two strains, LmjC and LmjM3 were selected as inoculum for seed coating. Two planting experiments were carried out in consecutive years under natural conditions in areas with edapho-climatic characteristics identical to those sustaining natural L. mariae-josephae populations, and successful reproduction of the plant was achieved. Interestingly, the successful reproductive cycle was absolutely dependent on seedling inoculation with effective bradyrhizobia, and optimal performance was observed in plants inoculated with LmjC, a strain that had previously shown the most efficient behavior under controlled conditions. Our results define conditions for L. mariae-josephae conservation and for extension to alkaline-limed soil habitats, where no other known lupine can thrive.

Research paper thumbnail of DmeRF system is required for nickel and cobalt resistance in Rhizobium leguminosarum bv. viciae

A Cation Diffusion Facilitator (CDF) family with high sequence identity to DmeF (Divalent Metal E... more A Cation Diffusion Facilitator (CDF) family with high sequence identity to DmeF (Divalent Metal Efflux) from Cupridavirus metallidurans was identified in Rhizobium leguminosarum bv. viciae UPM1137. The R.leguminosarum dmeF mutant strain was highly sensitive to Co2+ and moderately to Ni2+, but not to other metals like Zn2+, Cu2+ or Mn2+. Also, an open reading frame located downstream of DmeF in R.leguminosarum, designatged DmeR, encoding a protein homologous to the nickel and cobalt regulator RcnR from E.coli. Our R.leguminosarum SPF25 DmeRF mutant exhibited also a reduced sensitive in cobalt and nickel.

Research paper thumbnail of Metal Transport in the Rhizobium-Legume Symbiosis

Ecology and Applications, 2013

Research paper thumbnail of Fluorescence and Molecular Mechanics of 1-Methyl Naphthalenecarboxylate/Cyclodextrin Complexes in Aqueous Medium

Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007

Steady-state, time-resolved fluorescence and Molecular Mechanics techniques have been used to stu... more Steady-state, time-resolved fluorescence and Molecular Mechanics techniques have been used to study the complexation of 1-methyl naphthalenecarboxylate with three naturally occurring cyclodextrins (CDs). Emission spectra of 1MN show two overlapping electronic bands. The stoichiometry, the formation constants of the complexes and the thermodynamics parameters upon inclusion were obtained from the change of intensity ratios R of the maxima of both bands and AEsae with [CD] and temperature. As with the 2-methyl naphthalenecarboxylate (2MN) guest, 1:1 stoichiometries were obtained for all complexes. The formation constants, however, were relatively low compared to those obtained for 2MN. Geometry of the complexes from Molecular Mechanics in the presence of water agrees with the experimental stoichiometry of the complexes and the signs of enthalpy and entropy changes. Quenching, R at [CD] fi ¥ and fluorescence depolarization measurements also support the proposed structures. As with 2MN the inclusion is mostly dominated by van der Waals interactions.

Research paper thumbnail of Functional and Expression Analysis of the Metal-Inducible dmeRF System from Rhizobium leguminosarum bv. viciae

Applied and Environmental Microbiology, 2013

A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metal... more A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel-and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria.

Research paper thumbnail of Conservation of Endangered Lupinus mariae-josephae in Its Natural Habitat by Inoculation with Selected, Native Bradyrhizobium Strains

Lupinus mariae-josephae is a recently discovered endemism that is only found in alkaline-limed so... more Lupinus mariae-josephae is a recently discovered endemism that is only found in alkaline-limed soils, a unique habitat for lupines, from a small area in Valencia region (Spain). In these soils, L. mariae-josephae grows in just a few defined patches, and previous conservation efforts directed towards controlled plant reproduction have been unsuccessful. We have previously shown that L. mariae-josephae plants establish a specific root nodule symbiosis with bradyrhizobia present in those soils, and we reasoned that the paucity of these bacteria in soils might contribute to the lack of success in reproducing plants for conservation purposes. Greenhouse experiments using L. mariae-josephae trap-plants showed the absence or near absence of L. mariae-josephae-nodulating bacteria in ''terra rossa'' soils of Valencia outside of L. mariaejosephae plant patches, and in other ''terra rossa'' or alkaline red soils of the Iberian Peninsula and Balearic Islands outside of the Valencia L. mariae-josephae endemism region. Among the bradyrhizobia able to establish an efficient symbiosis with L. mariae-josephae plants, two strains, LmjC and LmjM3 were selected as inoculum for seed coating. Two planting experiments were carried out in consecutive years under natural conditions in areas with edapho-climatic characteristics identical to those sustaining natural L. mariae-josephae populations, and successful reproduction of the plant was achieved. Interestingly, the successful reproductive cycle was absolutely dependent on seedling inoculation with effective bradyrhizobia, and optimal performance was observed in plants inoculated with LmjC, a strain that had previously shown the most efficient behavior under controlled conditions. Our results define conditions for L. mariae-josephae conservation and for extension to alkaline-limed soil habitats, where no other known lupine can thrive.