| Lysobacter enzymogenes belong to Xanthomonadaceae,Lysobacter,and they have high GC%and motility ability.Lysobacter enzymogenes OH11 and C3 strains are known to be capable of producing many kinds of extracellular lytic enzymes and secondary metabolites,which made them have strong inhibitory effect against phytopathogens.These features promise a broad prospect in biocontrol activity.In this study,we wanted to identify preliminarily the genes which can regulate the biocontrol activity and surface motility in L.enzymogenes,and further investigate parts of these genes.TCSTSs(Two-Component Signal Transduction Systems)are a common and important signal transduction system.Its research dates back to many years ago and encompasses many strains to a larger or less extent.In the last decades indicate that the typical TSCTSs have two parts,HK(sensors histidine kinase)and RR(response regulators).In this study,wc identified 54 HK and 54 RR homolog proteins from L.enzymogenes OH11 genome via bioinformatic methods.And then,used protein domain and conserved regions to confirm the accuracy of the homology proteins.Finally,according to the different types of HK and RR,we distinguished the HK to 6 types and RR to 3 types and 12 subtypes.In summing up all the genes,we found 40 pairs of HK/RR protein,several of them being reported previously as virulence gene in Xanthomonas spp.In summary,we found whole TCSTSs in L.enzymogenes,which serves as a base for future research.HSAF(Heat-Stable Antifungal Factor)is a very important secondary metabolite in L.enzymogenes,which could inhibite fungal,oomucetes and nematodes.Our first goal was to study whether TCSTSs could control HSAF production in L.enzymogenes C3.Thtough preliminary selected,our research found 10 RR mutants reduced or lacked HSAF and 2 RR mutants enhanced HSAF,and all of these genes were belong to different gene families.These findings indicated that TCSTSs took parts in different cell functions and all these gene families could influence HSAF production.Furthermore we also found one of the increased genes belongs to Tyep IV Pili(T4P)family,suggesting that T4P might have some connection with TCSTSs.Type IV pili was a very common pili type.Usually,they are in one or both cell polar places to make twitching motility.In some pathogens,T4P could influence bacterial virulence.The cell In L.enzymogenes can move by itself although it lack of flagella,so we think this ability was closely related to T4P.And we also indicated that its biocontrol ability might be closed with T4P,in which there were many genes.We found 41 homolog genes in L.enzymogenes OH11,and 2 pairs TCSTSs genes and 5 orphan HK/RR proteins,which confirmed our thought above.We also found that OH11 lacks pilK、fimU and fimZ,but has two pilE/X/Y/V genes in comparison with P.aeruginosa,Furthermore,we also found there is a completed Pil-Chp gene cluster,containing RR proteins which enhance HSAF production in L.enzymogenes OH11.This result provided a relatively defined area for future research.Pil-Chp was found to be a chemotaxis system in the early research in T4P.According to the previous results,we chose the pilG and chpA,which belonged to TCSTSs and T4P,and ATPase gene pilB,which were in T4P,to further our research.We found that ChpA could interact with PilG,indicating they are atypical TCSTSs pair,and that there is,however,other protein intact with PilG.Moreover,AchpA,ApilG and ApilB could increase EPS production,but change twitching motility and colony morphology.We thought that all of these three genes were important in twitching motility.But ApilG and ApilB could enhance HSAF and WAP production and△chpA increased little of them;we indicated that chpA might be effected parts of the T4P function in L.enzymo,genes C3.Finally,all the results suggested that there was possibly a new regulate pathway in L.enzymogenes C3. |
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