Role and Regulation of Poly-3-Hydroxybutyrate in Nitrogen Fixation in Azorhizobium caulinodans.
Role and Regulation of Poly-3-Hydroxybutyrate in Nitrogen Fixation in Azorhizobium caulinodans.
复制标题
聚 3-羟基丁酸酯在 Azorhizobium caulinodans 固氮中的作用和调节。
DOI：
10.1094/mpmi-06-21-0138-r
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Crang N
中科院分区：
文献类型：
--
作者：
Crang N
茎瘤固氮根瘤菌phaC突变体（OPS 0865）不能产生聚-3-羟基丁酸酯（PHB），在许多碳源上生长不良，并且在实验室培养中不能固定氮。然而，当接种到其宿主植物，田菁rostrata，phaC突变体始终固定氮。从S.在Rostrataroot根瘤中，分离到抑制菌株（OPS 0921），其在实验室培养中显著改善了在各种碳源上的生长并且还固定氮。该抑制基因保留了原始突变，不能合成PHB。基因组测序显示，在phaR假定的核糖体结合位点（RBS）的ATG起始密码子上游13个碱基处存在一个抑制子转换突变，即G至A（位置357，354）。PhaR是PHB合成的全局调节剂，但在细胞内的调节中也具有其他作用。与野生型相比，在phaC突变体背景下，从phaR天然RBS的翻译增加了约6倍，这表明PhaR的水平受PHB控制。从抑制突变株（OPS 0921）的phaR突变RBS（RBS*）的翻译被锁定在低基础速率并且不受phaC突变的影响，这表明RBS* 使得PhaR水平对PHB的调节不敏感。在最初的alphaC突变体（OPS 0865）中，缺乏固氮和在许多碳源上生长不良可能是由于PhaR水平增加导致其复杂调节子的失调，因为PHB形成本身对于A中的有效固氮是不需要的。caulinodans.版权所有© 2021作者（s）.这是一篇开放获取的文章，在CC BY 4.0国际许可下分发。
AnAzorhizobium caulinodans phaCmutant (OPS0865) unable to make poly-3-hydroxybutyrate (PHB), grows poorly on many carbon sources and cannot fix nitrogen in laboratory culture. However, when inoculated onto its host plant,Sesbania rostrata,the phaCmutant consistently fixed nitrogen. Upon reisolation fromS. rostrataroot nodules, a suppressor strain (OPS0921) was isolated that has significantly improved growth on a variety of carbon sources and also fixes nitrogen in laboratory culture. The suppressor retains the original mutation and is unable to synthesize PHB. Genome sequencing revealed a suppressor transition mutation, G to A (position 357,354), 13 bases upstream of the ATG start codon ofphaRin its putative ribosome binding site (RBS). PhaR is the global regulator of PHB synthesis but also has other roles in regulation within the cell. In comparison with the wild type, translation from thephaRnative RBS is increased approximately sixfold in thephaCmutant background, suggesting that the level of PhaR is controlled by PHB. Translation from thephaRmutated RBS (RBS*) of the suppressor mutant strain (OPS0921) is locked at a low basal rate and unaffected by thephaCmutation, suggesting that RBS* renders the level of PhaR insensitive to regulation by PHB. In the originalphaCmutant (OPS0865), the lack of nitrogen fixation and poor growth on many carbon sources is likely to be due to increased levels of PhaR causing dysregulation of its complex regulon, because PHB formation, per se, is not required for effective nitrogen fixation inA. caulinodans.Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.