Filip'echeva Yulia, Shelud'ko Andrei, Prilipov Alexei, Telesheva Elizaveta, Mokeev Dmitry, Burov Andrei, Petrova Lilia, Katsy Elena
Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prospekt Entuziastov, Saratov, 410049, Russia.
Gamaleia Federal Research Centre for Epidemiology and Microbiology, Ministry of Health of the Russian Federation, 16 Gamalei, Moscow, 123098, Russia.
Folia Microbiol (Praha). 2018 Mar;63(2):147-153. doi: 10.1007/s12223-017-0543-6. Epub 2017 Aug 15.
Azospirillum brasilense has the ability of swimming and swarming motility owing to the work of a constitutive polar flagellum and inducible lateral flagella, respectively. The interplay between these flagellar systems is poorly understood. One of the key elements of the flagellar export apparatus is the protein FlhB. Two predicted flhB genes are present in the genome of A. brasilense Sp245 (accession nos. HE577327-HE577333). Experimental evidence obtained here indicates that the chromosomal coding sequence (CDS) AZOBR_150177 (flhB1) of Sp245 is essential for the production of both types of flagella. In an flhB1:: Omegon-Km mutant, Sp245.1063, defects in polar and lateral flagellar assembly and motility were complemented by expressing the wild-type flhB1 gene from plasmid pRK415. It was found that Sp245.1063 lost the capacity for slight but statistically significant decrease in mean cell length in response to transfer from solid to liquid media, and vice versa; in the complemented mutant, this capacity was restored. It was also shown that after the acquisition of the pRK415-harbored downstream CDS AZOBR_150176, cells of Sp245 and Sp245.1063 ceased to elongate on solid media. These initial data suggest that the AZOBR_150176-encoded putative multisensory hybrid sensor histidine kinase-response regulator, in concert with FlhB1, plays a role in morphological response of azospirilla to changes in the hardness of a milieu.
由于组成型极鞭毛和诱导型侧鞭毛的作用，巴西固氮螺菌分别具有游动和群体运动的能力。人们对这些鞭毛系统之间的相互作用了解甚少。鞭毛输出装置的关键元件之一是蛋白质FlhB。在巴西固氮螺菌Sp245的基因组中存在两个预测的flhB基因（登录号为HE577327 - HE577333）。此处获得的实验证据表明，Sp245的染色体编码序列（CDS）AZOBR_150177（flhB1）对于两种类型鞭毛的产生至关重要。在flhB1::Omegon - Km突变体Sp245.1063中，通过从质粒pRK415表达野生型flhB1基因，极鞭毛和侧鞭毛组装及运动的缺陷得到了互补。研究发现，Sp245.1063失去了在从固体培养基转移到液体培养基时平均细胞长度轻微但具有统计学显著下降的能力，反之亦然；在互补突变体中，这种能力得以恢复。还表明，在获得携带pRK415的下游CDS AZOBR_150176后，Sp245和Sp245.1063的细胞在固体培养基上不再伸长。这些初步数据表明，AZOBR_150176编码的假定多感官混合传感器组氨酸激酶 - 反应调节因子与FlhB1协同作用，在固氮螺菌对环境硬度变化的形态学反应中发挥作用。
