FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant.
FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant.
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固氮根瘤菌 FixJ 家族调节因子 AcfR 参与与宿主植物的共生
DOI：
10.1186/s12866-021-02138-w
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发表时间：
2021-03-09
期刊：
影响因子：
4.2
通讯作者：
Hu X
中科院分区：
文献类型：
--
作者：
Liu W;Bai X;Li Y;Zhang H;Hu X
细菌对环境条件的多种适应性反应是由信号转导途径介导的。双组分信号转导系统是细菌感知宿主植物信号并调整其相互作用行为的主要方式之一。在革兰氏阴性固氮菌茎瘤固氮根瘤菌ORS571中，共鉴定出7个开放阅读框，它们被认为是潜在的双组分反应调节因子。然而，迄今为止，这些反应调节因子在茎瘤固氮根瘤菌ORS571与宿主植物喙荚田菁共生相互作用中的生物学功能尚未阐明。
在本研究中，我们在茎瘤固氮根瘤菌ORS571中鉴定并研究了一种双组分反应调节因子AcfR，它具有可磷酸化的N端REC（接收）结构域和C端HTH（螺旋 - 转角 - 螺旋）LuxR DNA结合结构域。系统发育分析表明，AcfR与NarL / FixJ家族调节因子具有密切的进化关系。此外，预测有6种含有HATPase_c和HisKA结构域的组氨酸激酶可与AcfR相互作用。此外，通过比较野生型菌株和ΔacfR突变株，阐明了AcfR在自由生活和共生条件下的生物学功能。在自由生活状态下，与野生型菌株相比，ΔacfR突变株的细胞运动行为和胞外多糖产生显著降低。在共生状态下，ΔacfR突变株在宿主植物的茎和根上表现出竞争性结瘤缺陷，这表明AcfR可为茎瘤固氮根瘤菌提供有效的共生结瘤竞争能力。
我们的研究结果表明，AcfR作为一种反应调节因子，在自由生活条件下以及与宿主植物共生时调节茎瘤固氮根瘤菌的多种表型。本研究结果有助于阐明REC + HTH_LuxR双组分反应调节因子在根瘤菌 - 宿主植物相互作用中的作用。
在线版本包含补充材料，网址为10.1186/s12866 - 021 - 02138 - w。
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.
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影响因子：
4.2
作者：
Katsir G;Jarvis M;Phillips M;Ma Z;Gunsalus RP
通讯作者：
Gunsalus RP
影响因子：
2.9
作者：
Zhang, JH;Xiao, GP;Hubbell, WL
通讯作者：
Hubbell, WL
影响因子：
6.7
作者：
Ueda A;Wood TK
通讯作者：
Wood TK
影响因子：
64.5
作者：
DAVID, M;DAVERAN, ML;KAHN, D
通讯作者：
KAHN, D
DOI：
10.1073/pnas.76.4.1648
发表时间：
1979-01-01
影响因子：
11.1
作者：
FIGURSKI, DH;HELINSKI, DR
通讯作者：
HELINSKI, DR