http://www.ncbi.nlm.nih.gov/pubmed/23226379
PLoS One. 2012;7(11):e50768. doi: 10.1371/journal.pone.0050768. Epub 2012 Nov 30. Sinorhizobium meliloti sigma factors RpoE1 and RpoE4 are activated in stationary phase in response to sulfite.
Rhizobia- heimo on maabakteereita, jotka kykenevät fiksoimaan typpeä symbioosissa palkokasvien kanssa. (Kommentti Käytän herneen ja lupiinin sekä apilan kylvöä apuna juuri saadakseni mökilläni orgaanista typpeä fiksoiduksi epäorgaanisesta typestä eduksi marjapuskilleni)
Sekä maaperässä että aksveissa Rhizobia pitää kasvamattomuusjaksoja, jotka muistuttavat koeputkissa viljeltyjen bakteerien stationaarista vaihetta. ämän työn primäärinä kohteena on luonnehtia paremmin sitä geenisäätöä, mikä ilmenee Sinorhizobium meliloti- mikrobin biologisesti relevantissa kasvuvaiheessa.
Suomennos jatkuu...
Rhizobia
are soil bacteria able to establish a nitrogen-fixing symbiosis with
legume plants. Both in soil and in planta, rhizobia spend non-growing
periods resembling the stationary phase of in vitro-cultured bacteria.
The primary objective of this work was to better characterize gene
regulation in this biologically relevant growth stage in Sinorhizobium
meliloti.
By a tap-tag/mass spectrometry approach, we identified five sigma factors co-purifying with the RNA polymerase in stationary phase: the general stress response regulator RpoE2, the heat shock sigma factor RpoH2, and three extra-cytoplasmic function sigma factors (RpoE1, RpoE3 and RpoE4) belonging to the poorly characterized ECF26 subgroup.
We then showed that RpoE1 and RpoE4 i) are activated upon metabolism of sulfite-generating compounds (thiosulfate and taurine),
i) display overlapping regulatory activities,
iii) govern a dedicated sulfite response by controlling expression of the sulfite dehydrogenase SorT, iv) are activated in stationary phase, likely as a result of endogenous sulfite generation during bacterial growth.
We showed that SorT is required for optimal growth of S. meliloti in the presence of sulfite, suggesting that the response governed by RpoE1 and RpoE4 may be advantageous for bacteria in stationary phase either by providing a sulfite detoxification function or by contributing to energy production through sulfite respiration. This paper therefore reports the first characterization of ECF26 sigma factors, the first description of sigma factors involved in control of sulphur metabolism, and the first indication that endogenous sulfite may act as a signal for regulation of gene expression upon entry of bacteria in stationary phase.
By a tap-tag/mass spectrometry approach, we identified five sigma factors co-purifying with the RNA polymerase in stationary phase: the general stress response regulator RpoE2, the heat shock sigma factor RpoH2, and three extra-cytoplasmic function sigma factors (RpoE1, RpoE3 and RpoE4) belonging to the poorly characterized ECF26 subgroup.
We then showed that RpoE1 and RpoE4 i) are activated upon metabolism of sulfite-generating compounds (thiosulfate and taurine),
i) display overlapping regulatory activities,
iii) govern a dedicated sulfite response by controlling expression of the sulfite dehydrogenase SorT, iv) are activated in stationary phase, likely as a result of endogenous sulfite generation during bacterial growth.
We showed that SorT is required for optimal growth of S. meliloti in the presence of sulfite, suggesting that the response governed by RpoE1 and RpoE4 may be advantageous for bacteria in stationary phase either by providing a sulfite detoxification function or by contributing to energy production through sulfite respiration. This paper therefore reports the first characterization of ECF26 sigma factors, the first description of sigma factors involved in control of sulphur metabolism, and the first indication that endogenous sulfite may act as a signal for regulation of gene expression upon entry of bacteria in stationary phase.
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