Abstract
BACKGROUND: Soil bacteria collectively known as Rhizobium, characterized by their ability to establish beneficial symbiosis with legumes, share several common characteristics with pathogenic bacteria when infecting the host plant. Recently, it was demonstrated that a fadD mutant of Sinorhizobium meliloti is altered in the control of swarming, a type of co-ordinated movement previously associated with pathogenicity, and is also impaired in nodulation efficiency on alfalfa roots. In the phytopathogen Xanthomonas campestris, a fadD homolog (rpfB) forms part of a cluster of genes involved in the regulation of pathogenicity factors. In this work, we have investigated the role in swarming and symbiosis of SMc02161, a S. meliloti fadD-linked gene. RESULTS: The SMc02161 locus in S. meliloti shows similarities with members of the Major Facilitator Superfamily (MFS) of transporters. A S. meliloti null-mutant shows increased sensitivity to chloramphenicol. This indication led us to rename the locus tep1 for transmembrane efflux protein. The lack of tep1 does not affect the appearance of swarming motility. Interestingly, nodule formation efficiency on alfalfa plants is improved in the tep1 mutant during the first days of the interaction though nod gene expression is lower than in the wild type strain. Curiously, a nodC mutation or the addition of N-acetyl glucosamine to the wild type strain lead to similar reductions in nod gene expression as in the tep1 mutant. Moreover, aminosugar precursors of Nod factors inhibit nodulation. CONCLUSION: tep1 putatively encodes a transmembrane protein which can confer chloramphenicol resistance in S. meliloti by expelling the antibiotic outside the bacteria. The improved nodulation of alfalfa but reduced nod gene expression observed in the tep1 mutant suggests that Tep1 transports compounds which influence nodulation. In contrast to Bradyrhizobium japonicum, we show that in S. meliloti there is no feedback regulation of nodulation genes. Moreover, the Nod factor precursor, N-acetyl glucosamine reduces nod gene expression and nodulation efficiency when present at millimolar concentrations. A role for Tep1 in the efflux of Nod factor precursors could explain the phenotypes associated with tep1 inactivation.
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Claims 10
Claim · model-written summary
SMc02161 resembles MFS transporters.
- Taxon
- alfalfa
Medicago sativat0 - Interactor
- S. meliloti
Sinorhizobium melilotie0symbiont - Gene
- SMc02161e0
- Outcome
- similarities with members of the Major Facilitator Superfamily (MFS) of transporterse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The SMc02161 locus in S. meliloti shows similarities with members of the Major Facilitator Superfamily (MFS) of transporters”
t0“alfalfa plants”
Claim · model-written summary
The S. meliloti null mutant had increased chloramphenicol sensitivity.
- Taxon
- alfalfaMedicago sativat0
- Interactor
- S. melilotiSinorhizobium melilotie0symbiont
- Outcome
- S. meliloti null-mutant shows increased sensitivity to chloramphenicole0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A S. meliloti null-mutant shows increased sensitivity to chloramphenicol”
t0“alfalfa plants”
Claim · model-written summary
Loss of tep1 did not affect swarming appearance.
- Taxon
- alfalfaMedicago sativat0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Gene
- tep1e0
- Outcome
- appearance of swarming motilitye0
- Direction
- does not affecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The lack of tep1 does not affect the appearance of swarming motility”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
The tep1 mutant improved early alfalfa nodule formation efficiency.
- Taxon
- alfalfaMedicago sativae0
- Material
- tep1 mutante0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Outcome
- nodule formation efficiencye0
- Direction
- improvede0
- Qualifier
- during the first days of the interactione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nodule formation efficiency on alfalfa plants is improved in the tep1 mutant during the first days of the interaction”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
The tep1 mutant had lower nod gene expression than wild type.
- Taxon
- alfalfaMedicago sativat0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Gene
- nod genee0
- Outcome
- nod gene expressione0
- Direction
- lowere0
- Comparator
- wild type straine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nod gene expression is lower than in the wild type strain”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
A nodC mutation reduced nod gene expression similarly to tep1 mutation.
- Taxon
- alfalfaMedicago sativat0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Gene
- nodCe0
- Outcome
- nod gene expressione0
- Direction
- reductionse0
- Comparator
- tep1 mutante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a nodC mutation or the addition of N-acetyl glucosamine to the wild type strain lead to similar reductions in nod gene expression as in the tep1 mutant”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
N-acetyl glucosamine addition reduced nod gene expression similarly to tep1 mutation.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- addition of N-acetyl glucosaminee0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Outcome
- nod gene expressione0
- Direction
- reductionse0
- Comparator
- tep1 mutante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the addition of N-acetyl glucosamine to the wild type strain lead to similar reductions in nod gene expression as in the tep1 mutant”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
Aminosugar precursors of Nod factors inhibited nodulation.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- aminosugar precursors of Nod factorse0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Outcome
- nodulatione0
- Direction
- inhibite0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“aminosugar precursors of Nod factors inhibit nodulation”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
N-acetyl glucosamine at millimolar concentrations reduced nodulation efficiency.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- N-acetyl glucosaminee0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Outcome
- nodulation efficiencye0
- Direction
- reducese0
- Qualifier
- millimolar concentrationse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N-acetyl glucosamine reduces nod gene expression and nodulation efficiency when present at millimolar concentrations”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
Claim · model-written summary
N-acetyl glucosamine at millimolar concentrations reduced nod gene expression.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- N-acetyl glucosaminee0
- Interactor
- Sinorhizobium melilotiSinorhizobium melilotit0symbiont
- Outcome
- nod gene expressione0
- Direction
- reducese0
- Qualifier
- millimolar concentrationse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N-acetyl glucosamine reduces nod gene expression and nodulation efficiency when present at millimolar concentrations”
t0“Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants”
The same questions in other papers
N-acetylglucosamine · Sinorhizobium meliloti · Medicago sativa (alfalfa)Positive and negative results
1 in the opposite direction
- positive
nodulation factor · Sinorhizobium meliloti · Medicago sativa (alfalfa)Positive and negative results
3 in the opposite direction
- positive
- positive
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.