西瓜噬酸菌 DeoR 家族转录因子 glpR 的功能研究

Function of DeoR family transcription factor glpR in Acidovorax citrulli

摘要

DeoR (Deoxyribonucleoside operon repressor)家族转录因子是在原核生物中广泛存在的转录调控因子。DeoR 通过调节毒力因子的表达来影响病原细菌的致病性，并且在不同的病原细菌中有不同的调控网络。为了阐明 DeoR 在西瓜噬酸菌中的功能和信号通路，Aac5 菌株被用来构建 DeoR 转录因子 glpR 的缺失突变株及互补菌株，通过进行表型及转录水平的测定，对西瓜噬酸菌中 DeoR 转录因子 glpR 的功能进行初步探究。结果表明，缺失 glpR 基因后，Aac5 菌株利用果糖的能力、对西瓜苗的致病能力、西瓜子叶体内生长能力以及形成生物膜的能力均显著下降，体外生长速度减慢，而抗高盐胁迫能力以及抗铜离子胁迫能力显著增强。同时，基因 glpR 的缺失会导致三型分泌系统基因 hrpG、 hrpE 及 hrcJ 表达量显著下调，果糖利用相关基因 fruA、 fruB 与 fruK 表达量显著下调，生物膜相关基因 flgG 表达量显著下调，与 WT- fruBpGUS 相比，Δ glpR- fruBpGUS 的 fruB 的启动子活性显著减弱。以上结果表明， glpR 基因在西瓜噬酸菌果糖利用、抵抗逆境胁迫以及致病过程中起重要作用。

Abstract

The DeoR (Deoxyribonucleoside operon repressor) family of transcription factors are transcriptional regulators that are widely present in prokaryotes. DeoR affects the pathogenicity of pathogenic bacteria by regulating the expression of virulence factors, and there are different regulatory networks in different pathogenic bacteria. In order to elucidate its function and signaling pathway in Acidovorax citrulli, Aac5 strain was used to construct the deletion mutant and complementary strain of DeoR transcription factor glpR. The function of DeoR transcription factor glpR in Acidovorax citrulli was preliminarily explored by measuring the phenotype and transcription level. The results showed that after deletion of glpR gene, the ability of Aac5 strain to utilize fructose, the pathogenicity of watermelon seedlings, the growth ability of watermelon cotyledons and the ability to form biofilm were significantly decreased, and the growth rate in vitro was slowed down. The ability to resist high salt stress and copper ion stress was significantly increased. At the same time, the deletion of the gene glpR resulted in a significant down-regulation of the type III secretion system genes hrpG, hrpE and hrcJ, a significant down-regulation of the fructose utilization-related genes fruA, fruB and fruK, and a significant down-regulation of the biofilm-related gene flgG. Compared with WT- fruBpGUS, the promoter activity of fruB in Δ glpR- fruBpGUS was significantly reduced. The results indicated that glpR gene plays an important role in fructose utilization, resistance to stress and pathogenicity of Acidovorax citrulli.

关键词

西瓜噬酸菌 / 致病力 / DeoR 转录因子

Key words

Acidovorax citrulli / Virulence / DeoR transcription factor

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基金资助

国家重点研发计划(2023YFD1401200)

海南省科技专项(ZDYF2023XDNY084)

新疆维吾尔自治区重大科技专项(2023A02009)

新疆生产建设兵团科技攻关项目(2022AB015)

中国农业科学院科技创新工程(CAAS-ASTIP)

国家西甜瓜产业技术体系(CARS-25)