Role of an sRNA repeat in general stress response of alpha-proteobacteria and mechanisms of regulation

在α-蛋白细菌中鉴定小的非编码RNA仍处于早期阶段，对其生物学功能或作用机制知之甚少。我们已经在兼性光合作用细菌球形红假单胞菌中鉴定出17个在高氧压下丰富的sRNAs。SRNA RSs0680在染色体上发现有四个连续的拷贝(a-d)，并与一个未知功能的上游基因一起共转录。它的丰度在不同的胁迫条件下都会增加，即通过过氧化氢、单线态氧、超氧化物和热胁迫。与RSs0680高度相似的序列在其他α-蛋白细菌中也被发现，在所有情况下都是在一个以上拷贝的重复中发现的。为了更多地了解这个sRNA重复序列的功能，我们将删除或过度表达球状芽孢杆菌和/或上游ORF中的一些或全部拷贝，并分析几个拷贝的存在对功能的重要性。将对产生的突变体的转录组和蛋白质组进行研究。我们将识别靶向mRNAs，并阐明它们与RS0680的相互作用以及对调控的影响。将分析导致单个sRNA产生的处理事件。我们还将测试在脱氮副球藻和苜蓿中华根瘤菌中鉴定的同系物对不同压力的反应，并调查RSs0680在其他α-蛋白细菌中是否具有类似的作用。

The identification of small non-coding RNAs in alpha-proteobacteria is still at an early stage and little is known in regard to biological functions or mechanisms of action. We have identified 17 sRNAs, which are abundant under high oxygen tension in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. The sRNA RSs0680 was found in four consecutive copies (a-d) on the chromosome and is co-transcribed together with an upstream gene of unknown function. Its abundance is increased under various stress conditions, i.e. by peroxide, singlet oxygen, superoxide, and heat stress. Sequences with strong similarity to RSs0680 are found in other alpha-proteobacteria, in all cases in repeats of more than one copy. To learn more about the function of this sRNA repeat we will delete or over-express some or all of the copies in R. sphaeroides and/or the upstream ORF and analyze how important the presence of several copies is for function. The transcriptome and proteome of the resulting mutants will be investigated. We will identify the target mRNAs and elucidate their interaction to RSs0680 and the consequences for regulation. The processing events leading to the generation of the individual sRNAs will be analyzed. We will also test the response of the homologs identified in Paracoccus denitrificans and Sinorhizobium meliloti to different stresses and investigate whether RSs0680 has a similar role in other alpha-proteobacteria.