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

α-变形菌中小的非编码RNA的鉴定仍处于早期阶段，关于生物学功能或作用机制知之甚少。我们已经确定了17个sRNA，这是丰富的在高氧张力下的院系光合细菌Rhodobacter sphaeroides。sRNA RSs 0680在染色体上以四个连续拷贝（a-d）存在，并与功能未知的上游基因一起共转录。其丰度在各种胁迫条件下增加，即通过过氧化物、单线态氧、超氧化物和热胁迫。在其他α-变形菌中发现了与RS 0680高度相似的序列，在所有情况下都是一个以上拷贝的重复。为了更多地了解这种sRNA重复序列的功能，我们将删除或过度表达R中的部分或全部拷贝。sphaeroides和/或上游ORF，并分析几个拷贝的存在对于功能的重要性。将研究所得突变体的转录组和蛋白质组。我们将鉴定靶mRNA，并阐明它们与RSs 0680的相互作用以及调控的后果。将分析导致单个sRNA产生的加工事件。我们还将测试在Paracoccus ficans和Sinorhizobium meliloti中鉴定的同源物对不同胁迫的响应，并调查RSs 0680是否在其他α-变形菌中具有类似的作用。

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.