The two-component system ActJK is involved in acid stress tolerance and symbiosis in Sinorhizobium meliloti

Albicoro, Francisco Javier; Draghi, Walter Omar; Martini, María Carla; Salas, María Eugenia; Tejerizo, Gonzalo Arturo Torres; Lozano, Mauricio Javier; López, José Luis; Vacca, Carolina; Cafiero, Juan Hilario; Pistorio, Mariano; Bednarz, Hanna; Meier, Doreen; Lagares, Antonio; Niehaus, Karsten; Becker, Anke; Papa, María Florencia Del

doi:10.1016/j.jbiotec.2021.01.006

Cited by 10 publications

(13 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From an agronomic point of view, alfalfa plays an important and efficient role in the soils structuring and also in the contribution of nitrogen fertilization. Indeed, due to the fixation of atmospheric nitrogen by symbiotic rhizobia, alfalfa requires only small doses of this component in their mineral form (Albicoro et al 2021;Castellani et al 2021). In addition, alfalfa is known for its straight growth and its aerial part richness in nitrogenous matter (Zhang et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Assessment of Alfalfa (Medicago sativa L.) Cultivars for Salt Tolerance Based on Yield, Growth, Physiological, and Biochemical Traits

Guiza

Benabdelrahim

Brini

et al. 2021

J Plant Growth Regul

View full text Add to dashboard Cite

Alfalfa (Medicago sativa L.) is one of the most valuable forage crops having an intermediate salt-tolerant level. In this fact, twelve selected alfalfa from the south Tunisia oasis were subjected to salt stress looking for their adaptability against these abiotic constraints. Hence, this work reports the sodium chloride effect (150 mM) on the basis of biomass yield reduction. For this, some cultural, physiological, and biochemical parameters were monitored. Indeed, the relative water content, the stem and leaves aspects, chlorophyll content, protein amount, free proline amount, K + and Na + concentrations, protease and α-amylase activities, superoxide dismutase, and catalase ones were monitored. The findings give rise to no significant salinity effect on stem length and leaf number. However, there was a significant difference in leaf color for plants under salt stress. In addition, salinity decreases both fresh and dry weight of all cultivars. NaCl treatment significantly reduced chlorophyll content and the K + ion accumulations. Also, under salt stress, there was higher proline accumulation, Na + , and proteins in all alfalfa cultivars than under control. Additionally, these findings noticed the increase of enzymatic scavenging system related to the activity of superoxide dismutase, catalase, and protease under salt stress condition. In contrast, the α-amylase activity decreased under salt treatment. It seems from the studied parameters that our 12 alfalfa oasis cultivars are tolerant to salt stress under oasis conditions.

show abstract

Section: Introductionmentioning

confidence: 99%

Assessment of Alfalfa (Medicago sativa L.) Cultivars for Salt Tolerance Based on Yield, Growth, Physiological, and Biochemical Traits

Guiza

Benabdelrahim

Brini

et al. 2021

J Plant Growth Regul

View full text Add to dashboard Cite

show abstract

“…20 At pH 5.6, S. meliloti showed a reduced growth rate, but the cell titer counts documented that this pH were not yet lethal. 18 To more completely understand the regulation mediated by the ActJ response regulator in S. meliloti, we compared the protein expression profiles of S. meliloti 2011 wt and ΔactJ under acid and neutral conditions by using LC−MS/MS. Although growth differences were noticed in both the exponential and the stationary phases (Figure 1), the cells from the batch cultures were harvested at the mid-exponential phase (OD 600 0.5 ± 0.05, after monitoring growth with spectrophotometer cuvettes having an optical path length of 1 cm) to take advantage of the high protein synthesis at that stage.…”

Section: Identification Of Actj-regulated Proteins Under Neutral and ...mentioning

confidence: 93%

“…In S. meliloti, the deletion of the gene that encodes the response regulator protein ActJ of the TCS ActJK leads to a S. meliloti strain with impaired ability to grow under suboptimal acid conditions and results in negative impacts on rhizobia symbiotic life, such as a diminished nodule occupancy and impaired bacteroid differentiation. 18 In that initial work, we screened a S. meliloti mutant library to search for response regulator mutants with impaired ability to grow in a suboptimal acid condition. Such stress condition was previously established as pH 5.6 because S. meliloti was not able to grow below pH 5.6, whereas in the range of pH between 5.8 and 7.0, only minor deviations from the growth curve at pH 7.0 occurred.…”

Section: Identification Of Actj-regulated Proteins Under Neutral and ...mentioning

confidence: 98%

See 1 more Smart Citation

Comparative Proteomic Analysis Revealing ActJ-Regulated Proteins in Sinorhizobium meliloti

et al. 2023

Self Cite

View full text Add to dashboard Cite

To adapt to different environmental conditions, Sinorhizobium meliloti relies on finely tuned regulatory networks, most of which are unexplored to date. We recently demonstrated that deletion of the two-component system ActJK renders an acid-vulnerable phenotype in S. meliloti and negatively impacts bacteroid development and nodule occupancy as well. To fully understand the role of ActJ in acid tolerance, S. meliloti wild-type and S. meliloti ΔactJ proteomes were compared in the presence or absence of acid stress by nanoflow ultrahigh-performance liquid chromatography coupled to mass spectrometry. The analysis demonstrated that proteins involved in the synthesis of exopolysaccharides (EPSs) were notably enriched in ΔactJ cells in acid pH. Total EPS quantification further revealed that although EPS production was augmented at pH 5.6 in both the ΔactJ and the parental strain, the lack of ActJ significantly enhanced this difference. Moreover, several efflux pumps were found to be downregulated in the ΔactJ strain. Promoter fusion assays suggested that ActJ positively modulated its own expression in an acid medium but not at under neutral conditions. The results presented here identify several ActJ-regulated genes in S. meliloti, highlighting key components associated with ActJK regulation that will contribute to a better understanding of rhizobia adaptation to acid stress.

show abstract

“…These cellular lifestyles occur in very different environments and the soil environment particularly can involve widely varying physicochemical conditions. Accordingly, S. meliloti has been the subject of attempts to identify genes that when disrupted conditionally impair growth under stressful conditions that include high salinity (Wei et al, 2004;Domínguez-Ferreras et al, 2006;Miller-Williams et al, 2006;Vriezen et al, 2013;Calatrava-Morales et al, 2017), low pH (Reeve et al, 1998;Lagares et al, 2016;Albicoro et al, 2021), oxidative stress (Davies and Walker, 2007;Flechard et al, 2009;Lehman and Long, 2018) and other physical or chemical conditions.…”

Section: Introductionmentioning

confidence: 99%

The two-component regulatory system CenK–CenR regulates expression of a previously uncharacterized protein required for salinity and oxidative stress tolerance in Sinorhizobium meliloti

Bensig

Valadez-Cano²,

Kuang³

et al. 2022

Front. Microbiol.

View full text Add to dashboard Cite

Genes of unknown function constitute a considerable fraction of most bacterial genomes. In a Tn5-based search for stress response genes in the nitrogen-fixing facultative endosymbiont Sinorhizobium (Ensifer) meliloti, we identified a previously uncharacterized gene required for growth on solid media with increased NaCl concentrations. The encoded protein carries a predicted thioredoxin fold and deletion of the gene also results in increased sensitivity to hydrogen peroxide and cumene hydroperoxide. We have designated the gene srlA (stress resistance locus A) based on these phenotypes. A deletion mutant yields phenotypic revertants on high salt medium and genome sequencing revealed that all revertants carry a mutation in genes homologous to either cenK or cenR. srlA promoter activity is abolished in these revertant host backgrounds and in a strain carrying a deletion in cenK. We also observed that the srlA promoter is autoregulated, displaying low activity in a wildtype (wt) host background and high activity in the srl deletion mutant background. The srlA promoter includes a conserved inverted repeat directly upstream of the predicted −35 subsequence. A mutational analysis demonstrated that the site is required for the high promoter activity in the srlA deletion background. Electromobility shift assays using purified wildtype CenR response regulator and a D55E phosphomimetic derivative suggest this protein acts as a likely Class II activator by binding promoter DNA. These results document the first identified CenK–CenR regulon member in S. meliloti and demonstrate this two-component regulatory system and gene srlA influences cellular growth and persistence under certain stress-inducing conditions.

show abstract

The two-component system ActJK is involved in acid stress tolerance and symbiosis in Sinorhizobium meliloti

Cited by 10 publications

References 65 publications

Assessment of Alfalfa (Medicago sativa L.) Cultivars for Salt Tolerance Based on Yield, Growth, Physiological, and Biochemical Traits

Assessment of Alfalfa (Medicago sativa L.) Cultivars for Salt Tolerance Based on Yield, Growth, Physiological, and Biochemical Traits

Comparative Proteomic Analysis Revealing ActJ-Regulated Proteins in Sinorhizobium meliloti

The two-component regulatory system CenK–CenR regulates expression of a previously uncharacterized protein required for salinity and oxidative stress tolerance in Sinorhizobium meliloti

Contact Info

Product

Resources

About