scholarly journals AcheZ-Like Gene inAzorhizobium caulinodansIs a Key Gene in the Control of Chemotaxis and Colonization of the Host Plant

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Xiaolin Liu ◽  
Wei Liu ◽  
Yu Sun ◽  
Chunlei Xia ◽  
Claudine Elmerich ◽  
...  
Keyword(s):  
Host Plant ◽  
Active Site ◽  
Deletion Mutant ◽  
Sinorhizobium Meliloti ◽  
Response Regulator ◽  
General Situation ◽  
Symbiotic Association ◽  
Azorhizobium Caulinodans ◽  
Content Type ◽  
In The Wild

ABSTRACTChemotaxis can provide bacteria with competitive advantages for survival in complex environments. The CheZ chemotaxis protein is a phosphatase, affecting the flagellar motor inEscherichia coliby dephosphorylating the response regulator phosphorylated CheY protein (CheY∼P) responsible for clockwise rotation. AcheZgene has been found inAzorhizobium caulinodansORS571, in contrast to other rhizobial species studied so far. The CheZ protein in strain ORS571 has a conserved motif similar to that corresponding to the phosphatase active site inE. coli. The construction of acheZdeletion mutant strain and ofcheZmutant strains carrying a mutation in residues of the putative phosphatase active site showed that strain ORS571 participates in chemotaxis and motility, causing a hyperreversal behavior. In addition, the properties of thecheZdeletion mutant revealed that ORS571 CheZ is involved in other physiological processes, since it displayed increased flocculation, biofilm formation, exopolysaccharide (EPS) production, and host root colonization. In particular, it was observed that the expression of severalexpgenes, involved in EPS synthesis, was upregulated in thecheZmutant compared to that in the wild type, suggesting that CheZ negatively controlsexpgene expression through an unknown mechanism. It is proposed that CheZ influences theAzorhizobium-plant association by negatively regulating early colonization via the regulation of EPS production. This report established that CheZ inA. caulinodansplays roles in chemotaxis and the symbiotic association with the host plant.IMPORTANCEChemotaxis allows bacteria to swim toward plant roots and is beneficial to the establishment of various plant-microbe associations. The level of CheY phosphorylation (CheY∼P) is central to the chemotaxis signal transduction. The mechanism of the signal termination of CheY∼P remains poorly characterized amongAlphaproteobacteria, except forSinorhizobium meliloti, which does not contain CheZ but which controls CheY∼P dephosphorylation through a phosphate sink mechanism.Azorhizobium caulinodansORS571, a microsymbiont ofSesbania rostrata, has an orphancheZgene besides twocheYgenes similar to those inS. meliloti. In addition to controlling the chemotaxis response, the CheZ-like protein in strain ORS571 is playing a role by decreasing bacterial adhesion to the host plant, in contrast to the general situation where chemotaxis-associated proteins promote adhesion. In this study, we identified a CheZ-like protein amongAlphaproteobacteriafunctioning in chemotaxis and theA. caulinodans-S. rostratasymbiosis.

scholarly journals The Sinorhizobium melilotintrXGene Is Involved in Succinoglycan Production, Motility, and Symbiotic Nodulation on Alfalfa

2013 ◽  
Vol 79 (23) ◽  
pp. 7150-7159 ◽  
Author(s):  
Dong Wang ◽  
Haiying Xue ◽  
Yiwen Wang ◽  
Ruochun Yin ◽  
Fang Xie ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Nitrogen Starvation ◽  
Response Regulator ◽  
Insertion Mutant ◽  
Sesbania Rostrata ◽  
Symbiotic Relationship ◽  
Azorhizobium Caulinodans ◽  
Free Living ◽  
Content Type ◽  
Regulatory Systems

ABSTRACTRhizobia establish a symbiotic relationship with their host legumes to induce the formation of nitrogen-fixing nodules. This process is regulated by many rhizobium regulators, including some two-component regulatory systems (TCSs). NtrY/NtrX, a TCS that was first identified inAzorhizobium caulinodans, is required for free-living nitrogen metabolism and symbiotic nodulation onSesbania rostrata. However, its functions in a typical rhizobium such asSinorhizobium melilotiremain unclear. Here we found that theS. melilotiresponse regulator NtrX but not the histidine kinase NtrY is involved in the regulation of exopolysaccharide production, motility, and symbiosis with alfalfa. A plasmid insertion mutant ofntrXformed mucous colonies, which overproduced succinoglycan, an exopolysaccharide, by upregulating its biosynthesis genes. This mutant also exhibited motility defects due to reduced flagella and decreased expression of flagellins and regulatory genes. The regulation is independent of the known regulatory systems of ExoR/ExoS/ChvI, EmmABC, and ExpR. Alfalfa plants inoculated with thentrXmutant were small and displayed symptoms of nitrogen starvation. Interestingly, the deletion mutant ofntrYshowed a phenotype similar to that of the parent strain. These findings demonstrate that theS. melilotiNtrX is a new regulator of succinoglycan production and motility that is not genetically coupled with NtrY.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

scholarly journals Cellular Stoichiometry of Chemotaxis Proteins in Sinorhizobium meliloti

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Timofey D. Arapov ◽  
Rafael Castañeda Saldaña ◽  
Amanda L. Sebastian ◽  
W. Keith Ray ◽  
Richard F. Helm ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Sinorhizobium Meliloti ◽  
Response Regulator ◽  
Bacterial Chemotaxis ◽  
Adaptor Proteins ◽  
Molar Ratio ◽  
Content Type ◽  
Chemotaxis Proteins ◽  
Chemotaxis System

ABSTRACT Chemotaxis systems enable microbes to sense their immediate environment, moving toward beneficial stimuli and away from those that are harmful. In an effort to better understand the chemotaxis system of Sinorhizobium meliloti, a symbiont of the legume alfalfa, the cellular stoichiometries of all ten chemotaxis proteins in S. meliloti were determined. A combination of quantitative immunoblot and mass spectrometry revealed that the protein stoichiometries in S. meliloti varied greatly from those in Escherichia coli and Bacillus subtilis. To compare protein ratios to other systems, values were normalized to the central kinase CheA. All S. meliloti chemotaxis proteins exhibited increased ratios to various degrees. The 10-fold higher molar ratio of adaptor proteins CheW1 and CheW2 to CheA might result in the formation of rings in the chemotaxis array that consist of only CheW instead of CheA and CheW in a 1:1 ratio. We hypothesize that the higher ratio of CheA to the main response regulator CheY2 is a consequence of the speed-variable motor in S. meliloti, instead of a switch-type motor. Similarly, proteins involved in signal termination are far more abundant in S. meliloti, which utilizes a phosphate sink mechanism based on CheA retrophosphorylation to inactivate the motor response regulator versus CheZ-catalyzed dephosphorylation as in E. coli and B. subtilis. Finally, the abundance of CheB and CheR, which regulate chemoreceptor methylation, was increased compared to CheA, indicative of variations in the adaptation system of S. meliloti. Collectively, these results mark significant differences in the composition of bacterial chemotaxis systems. IMPORTANCE The symbiotic soil bacterium Sinorhizobium meliloti contributes greatly to host-plant growth by fixing atmospheric nitrogen. The provision of nitrogen as ammonium by S. meliloti leads to increased biomass production of its legume host alfalfa and diminishes the use of environmentally harmful chemical fertilizers. To better understand the role of chemotaxis in host-microbe interaction, a comprehensive catalogue of the bacterial chemotaxis system is vital, including its composition, function, and regulation. The stoichiometry of chemotaxis proteins in S. meliloti has very few similarities to the systems in Escherichia coli and Bacillus subtilis. In addition, total amounts of proteins are significantly lower. S. meliloti exhibits a chemotaxis system distinct from known models by incorporating new proteins as exemplified by the phosphate sink mechanism.

scholarly journals FadD Is Required for Utilization of Endogenous Fatty Acids Released from Membrane Lipids

2011 ◽  
Vol 193 (22) ◽  
pp. 6295-6304 ◽  
Author(s):  
Ángel Pech-Canul ◽  
Joaquina Nogales ◽  
Alfonso Miranda-Molina ◽  
Laura Álvarez ◽  
Otto Geiger ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Stationary Phase ◽  
Free Fatty Acids ◽  
Sinorhizobium Meliloti ◽  
Membrane Lipids ◽  
Membrane Phospholipids ◽  
Content Type ◽  
Fatty Acid Transporter ◽  
In The Wild

FadD is an acyl coenzyme A (CoA) synthetase responsible for the activation of exogenous long-chain fatty acids (LCFA) into acyl-CoAs. Mutation offadDin the symbiotic nitrogen-fixing bacteriumSinorhizobium melilotipromotes swarming motility and leads to defects in nodulation of alfalfa plants. In this study, we found thatS. melilotifadDmutants accumulated a mixture of free fatty acids during the stationary phase of growth. The composition of the free fatty acid pool and the results obtained after specific labeling of esterified fatty acids with a Δ5-desaturase (Δ5-Des) were in agreement with membrane phospholipids being the origin of the released fatty acids.Escherichia colifadDmutants also accumulated free fatty acids released from membrane lipids in the stationary phase. This phenomenon did not occur in a mutant ofE. coliwith a deficient FadL fatty acid transporter, suggesting that the accumulation of fatty acids infadDmutants occurs inside the cell. Our results indicate that, besides the activation of exogenous LCFA, in bacteria FadD plays a major role in the activation of endogenous fatty acids released from membrane lipids. Furthermore, expression analysis performed withS. melilotirevealed that a functional FadD is required for the upregulation of genes involved in fatty acid degradation and suggested that in the wild-type strain, the fatty acids released from membrane lipids are degraded by β-oxidation in the stationary phase of growth.

scholarly journals Positive Regulation of Leptospira interrogans kdp Expression by KdpE as Demonstrated with a Novel β-Galactosidase Reporter in Leptospira biflexa

2012 ◽  
Vol 78 (16) ◽  
pp. 5699-5707 ◽  
Author(s):  
James Matsunaga ◽  
Mariana L. Coutinho
Keyword(s):  
Gene Expression ◽  
Response Regulator ◽  
Regulation Of Gene Expression ◽  
Leptospira Interrogans ◽  
Mrna Levels ◽  
Genetic Circuits ◽  
Positive Regulation ◽  
Content Type ◽  
Novel Approach ◽  
In The Wild

ABSTRACTLeptospirosis is a potentially deadly zoonotic disease that afflicts humans and animals.Leptospira interrogans, the predominant agent of leptospirosis, encounters diverse conditions as it proceeds through its life cycle, which includes stages inside and outside the host. Unfortunately, the number of genetic tools available for examining the regulation of gene expression inL. interrogansis limited. Consequently, little is known about the genetic circuits that control gene expression inLeptospira. To better understand the regulation of leptospiral gene expression, theL. interrogans kdplocus, encoding homologs of the P-type ATPase KdpABC potassium transporter with their KdpD sensors and KdpE response regulators, was selected for analysis. We showed that akdpEmutation inL. interrogansprevented the increase inkdpABCmRNA levels observed in the wild-typeL. interrogansstrain when external potassium levels were low. To confirm that KdpE was a positive regulator ofkdpABCtranscription, we developed a novel approach for constructing chromosomal genetic fusions to the endogenousbgaL(β-galactosidase) gene of the nonpathogenLeptospira biflexa. We demonstrated positive regulation of akdpA′-bgaLfusion inL. biflexaby theL. interrogansKdpE response regulator. A controllipL32′-bgaLfusion was not regulated by KdpE. These results demonstrate the utility of genetic fusions to thebgaLgene ofL. biflexafor examining leptospiral gene regulation.

scholarly journals Serratia marcescensarn, a PhoP-Regulated Locus Necessary for Polymyxin B Resistance

2014 ◽  
Vol 58 (9) ◽  
pp. 5181-5190 ◽  
Author(s):  
Quei Yen Lin ◽  
Yi-Lin Tsai ◽  
Ming-Che Liu ◽  
Wei-Cheng Lin ◽  
Po-Ren Hsueh ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Challenge Test ◽  
Polymyxin B ◽  
Resistant Bacteria ◽  
Wild Type ◽  
Mobility Shift ◽  
Content Type ◽  
In The Wild

ABSTRACTPolymyxins, which are increasingly being used to treat infections caused by multidrug-resistant bacteria, perform poorly againstSerratia marcescens. To investigate the underlying mechanisms, Tn5mutagenesis was performed and two mutants exhibiting increased polymyxin B (PB) susceptibility were isolated. The mutants were found to have Tn5inserted into thearnBandarnCgenes. In other bacteria,arnBandarnCbelong to the seven-genearnoperon, which is involved in lipopolysaccharide (LPS) modification. LPSs ofarnmutants had greater PB-binding abilities than that of wild-type LPS. Further, we identified PhoP, a bacterial two-component response regulator, as a regulator of PB susceptibility inS. marcescens. By the reporter assay, we found PB- and low-Mg2+-induced expression ofphoPandarnin the wild-type strain but not in thephoPmutant. Complementation of thephoPmutant with the full-lengthphoPgene restored the PB MIC and induction by PB and low Mg2+levels, as in the wild type. An electrophoretic mobility shift assay (EMSA) further demonstrated that PhoP bound directly to thearnpromoter. The PB challenge test confirmed that pretreatment with PB and low Mg2+levels protectedS. marcescensfrom a PB challenge in the wild-type strain but not in thephoPmutant. Real-time reverse transcriptase-PCR also indicated that PB serves as a signal to regulate expression ofugd, a gene required for LPS modification, inS. marcescensthrough a PhoP-dependent pathway. Finally, we found that PB-resistant clinical isolates displayed greater expression ofarnAupon exposure to PB than did susceptible isolates. This is the first report to describe the role ofS. marcescensarnin PB resistance and its modulation by PB and Mg2+through the PhoP protein.

scholarly journals Host Plant Determines the Population Size of an Obligate Symbiont (Buchnera aphidicola) in Aphids

2016 ◽  
Vol 82 (8) ◽  
pp. 2336-2346 ◽  
Author(s):  
Yuan-Chen Zhang ◽  
Wen-Jie Cao ◽  
Le-Rong Zhong ◽  
H. Charles J. Godfray ◽  
Xiang-Dong Liu
Keyword(s):  
Host Plant ◽  
Population Size ◽  
Plant Extracts ◽  
Host Plants ◽  
Aphis Gossypii ◽  
Buchnera Aphidicola ◽  
Content Type ◽  
Two Generations ◽  
Novel Host ◽  
In The Wild

ABSTRACTBuchnera aphidicolais an obligate endosymbiont that provides aphids with several essential nutrients. Though much is known about aphid-Buchnerainteractions, the effect of the host plant onBuchnerapopulation size remains unclear. Here we used quantitative PCR (qPCR) techniques to explore the effects of the host plant onBuchneradensities in the cotton-melon aphid,Aphis gossypii.Buchneratiters were significantly higher in populations that had been reared on cucumber for over 10 years than in populations maintained on cotton for a similar length of time. Aphids collected in the wild from hibiscus and zucchini harbored moreBuchnerasymbionts than those collected from cucumber and cotton. The effect of aphid genotype on the population size ofBuchneradepended on the host plant upon which they fed. When aphids from populations maintained on cucumber or cotton were transferred to novel host plants, host survival andBuchnerapopulation size fluctuated markedly for the first two generations before becoming relatively stable in the third and later generations. Host plant extracts from cucumber, pumpkin, zucchini, and cowpea added to artificial diets led to a significant increase inBuchneratiters in the aphids from the population reared on cotton, while plant extracts from cotton and zucchini led to a decrease inBuchneratiters in the aphids reared on cucumber. Gossypol, a secondary metabolite from cotton, suppressedBuchnerapopulations in populations from both cotton and cucumber, while cucurbitacin from cucurbit plants led to higher densities. Together, the results suggest that host plants influenceBuchnerapopulation processes and that this may provide phenotypic plasticity in host plant use for clonal aphids.

scholarly journals Contributions of Sinorhizobium meliloti Transcriptional Regulator DksA to Bacterial Growth and Efficient Symbiosis with Medicago sativa

2016 ◽  
Vol 198 (9) ◽  
pp. 1374-1383 ◽  
Author(s):  
Kathrin Wippel ◽  
Sharon R. Long
Keyword(s):  
Medicago Sativa ◽  
Host Plant ◽  
Sinorhizobium Meliloti ◽  
Coiled Coil ◽  
Regulatory System ◽  
Stringent Response ◽  
Transcriptional Regulator ◽  
Molecular Control ◽  
Content Type ◽  
Nitrogen Fixation Activity

ABSTRACTThe stringent response, mediated by the (p)ppGpp synthetase RelA and the RNA polymerase-binding protein DksA, is triggered by limiting nutrient conditions. For some bacteria, it is involved in regulation of virulence. We investigated the role of two DksA-like proteins from the Gram-negative nitrogen-fixing symbiontSinorhizobium melilotiin free-living culture and in interaction with its host plantMedicago sativa. The two paralogs, encoded by the genesSMc00469andSMc00049, differ in the constitution of two major domains required for function in canonical DksA: the DXXDXA motif at the tip of a coiled-coil domain and a zinc finger domain. Using mutant analyses of single, double, and triple deletions forSMc00469(designateddksA),SMc00049, andrelA, we found that the ΔdksAmutant but not the ΔSMc00049mutant showed impaired growth on minimal medium, reduced nodulation on the host plant, and lower nitrogen fixation activity in early nodules, while itsnodgene expression was normal. The ΔrelAmutant showed severe pleiotropic phenotypes under all conditions tested. OnlyS. melilotidksAcomplemented the metabolic defects of anEscherichia coli dksAmutant. Modifications of the DXXDXA motif in SMc00049 failed to establish DksA function. Our results imply a role for transcriptional regulator DksA in theS. meliloti-M. sativasymbiosis.IMPORTANCEThe stringent response is a bacterial transcription regulation process triggered upon nutritional stress.Sinorhizobium meliloti, a soil bacterium establishing agriculturally important root nodule symbioses with legume plants, undergoes constant molecular adjustment during host interaction. Analyzing the components of the stringent response in this alphaproteobacterium helps understand molecular control regarding the development of plant interaction. Using mutant analyses, we describe how the lack of DksA influences symbiosis withMedicago sativaand show that a second paralogousS. melilotiprotein cannot substitute for this missing function. This work contributes to the field by showing the similarities and differences ofS. melilotiDksA-like proteins to orthologs from other species, adding information to the diversity of the stringent response regulatory system.

scholarly journals NAD(P)+-Malic Enzyme Mutants of Sinorhizobium sp. Strain NGR234, but Not Azorhizobium caulinodans ORS571, Maintain Symbiotic N2Fixation Capabilities

2012 ◽  
Vol 78 (8) ◽  
pp. 2803-2812 ◽  
Author(s):  
Ye Zhang ◽  
Toshihiro Aono ◽  
Phillip Poole ◽  
Turlough M. Finan
Keyword(s):  
Malic Enzyme ◽  
Sinorhizobium Meliloti ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Rhizobium Leguminosarum ◽  
Dicarboxylic Acids ◽  
Dry Weight ◽  
Tca Cycle ◽  
Broad Host Range ◽  
Azorhizobium Caulinodans ◽  
Content Type

ABSTRACTC4-dicarboxylic acids appear to be metabolized via the tricarboxylic acid (TCA) cycle in N2-fixing bacteria (bacteroids) within legume nodules. InSinorhizobium melilotibacteroids from alfalfa, NAD+-malic enzyme (DME) is required for N2fixation, and this activity is thought to be required for the anaplerotic synthesis of pyruvate. In contrast, in the pea symbiontRhizobium leguminosarum, pyruvate synthesis occurs via either DME or a pathway catalyzed by phosphoenolpyruvate carboxykinase (PCK) and pyruvate kinase (PYK). Here we report thatdmemutants of the broad-host-rangeSinorhizobiumsp. strain NGR234 formed nodules whose level of N2fixation varied from 27 to 83% (plant dry weight) of the wild-type level, depending on the host plant inoculated. NGR234 bacteroids had significant PCK activity, and while singlepckAand singledmemutants fixed N2at reduced rates, apckA dmedouble mutant had no N2-fixing activity (Fix−). Thus, NGR234 bacteroids appear to synthesize pyruvate from TCA cycle intermediates via DME or PCK pathways. These NGR234 data, together with other reports, suggested that the completely Fix−phenotype ofS. meliloti dmemutants may be specific to the alfalfa-S. melilotisymbiosis. We therefore examined the ME-like genesazc3656andazc0119fromAzorhizobium caulinodans, asazc3656mutants were previously shown to form Fix−nodules on the tropical legumeSesbania rostrata. We found that purified AZC3656 protein is an NAD(P)+-malic enzyme whose activity is inhibited by acetyl-coenzyme A (acetyl-CoA) and stimulated by succinate and fumarate. Thus, whereas DME is required for symbiotic N2fixation inA. caulinodansandS. meliloti, in other rhizobia this activity can be bypassed via another pathway(s).

scholarly journals The LsrB Protein Is Required for Agrobacterium tumefaciens Interaction with Host Plants

2018 ◽  
Vol 31 (9) ◽  
pp. 951-961 ◽  
Author(s):  
Guirong Tang ◽  
Qiong Li ◽  
Shenghui Xing ◽  
Ningning Li ◽  
Zheng Tang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Agrobacterium Tumefaciens ◽  
Host Plant ◽  
Host Plants ◽  
Deletion Mutant ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Detoxification Enzymes ◽  
Sequencing Analysis ◽  
Type Iv

Agrobacterium tumefaciens infects and causes crown galls in dicot plants by transferring T-DNA from the Ti plasmid to the host plant via a type IV secretion system. This process requires appropriate environmental conditions, certain plant secretions, and bacterial regulators. In our previous work, a member of the LysR family of transcriptional regulators (LsrB) in Sinorhizobium meliloti was found to modulate its symbiotic interactions with the host plant alfalfa. However, the function of its homolog in A. tumefaciens remains unclear. In this study, we show that the LsrB protein of A. tumefaciens is required for efficient transformation of host plants. A lsrB deletion mutant of A. tumefaciens exhibits a number of defects, including in succinoglycan production, attachment, and resistance to oxidative stress and iron limitation. RNA-sequencing analysis indicated that 465 genes were significantly differentially expressed (upregulation of 162 genes and downregulation of 303 genes) in the mutant, compared with the wild-type strain, including those involved in succinoglycan production, iron transporter, and detoxification enzymes for oxidative stress. Moreover, expression of the lsrB gene from S. meliloti, Brucella abortus, or A. tumefaciens rescued the defects observed in the S. meliloti or A. tumefaciens lsrB deletion mutant. Our findings suggest that a conserved mechanism of LsrB function exists in symbiotic and pathogenic bacteria of the family Rhizobiaceae.

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