Identification,Location And Function Analysis Of G-Quadrupexes In Electricigens

Electricigens have attracted much attention due to the capacity of electricity production. the key step of the electricity production is extracellular electron transfer(EET). However, currently the key genes and their regulation involved in EET pathways are not clear. G-quadruplex is a special DNA secondary structure which play a crucial role in telomeres protection, DNA replication, gene recombination and especially gene express regulation.Besides the canonical double helix, DNA can fold into a special secondary structure G-quadruplex. Studies found that the G-quadrupexes play crucial roles in telomeres protection, DNA replication and gene recombination, especially gene expression regulation. In this paper, we focus on the impact of G-quadruplexes on EET in Geobacter and S. oneidensis MR-1. Each side set forth EET related important genes and their expression regulation from a new perspective, which might provide certain information to clarify EET.The main results are listed as follows:1. The identification and location of G-quadrupexes. First we identified the G-quadrupexes in 9 strains for Geobcater and S. oneidensis MR-1 genome. Then we examined the distribution of G-quadrupexes located in transcriptional regulatory region. It was discovered that the amount of G-quadrupexes had a drop within the-15bp upstream up to +15 bp downstream of the Transcription Start Site(TSS), but within the+15bp up to+130bp downstream of TSS. The amount of G-quadrupexes was maximum. The results confirmed that the G-quadrupexes were not random distribution, and were associated with gene expression regulation.2. We analyzed function of G-quadrupexes in G. sulfurreducens PCA and S. oneidensis MR-1. First we studied the function of G-quadrupexes in G. sulfurreducens PCA and S. oneidensis MR-1. It was observed that G-quadruplex genes had both common function and special function. Then we studied the special function. In G. sulfurreducens PCA, among type VI secretion system related 13 genes, there were 10 G-quadruplex genes. In S. oneidensis MR-1, among electron transport chain related 22 genes, there were 5 G-quadruplex genes. By means of expression analysis, we found these G-quadruplex genes had special regulatory mechanism. Last we analyzed EET related genes in G. sulfurreducens PCA and S. oneidensis MR-1. It was found there were 15 EET related G-quadruplex genes in G. sulfurreducens PCA, of which omcH,ompB and omcO had a regulation effect on EET. But in S. oneidensis MR-1, we didn't have similar findings.3. We analyzed the evolutionary relationships of G-quadruplexes across Geobacter strains. First we studied the relationship between conservation and evolutionary distance. We found that G-quadruplexes were more conserved if the evolutionary distance were closer. Then we studied the conservation of EET related G-quadruplex genes in G. sulfurreducens PCA, it was observed that they had a certain degree conservation. Meanwhile we studied the conservative omcO and cbcN found if we transformed the structure of G-quadruplex, the EET pathway wound change.In summary, We systematically studied indentification, loacation, and function analysis of G-quadruplexes and conservation of EET related G-quadruplex genes respectively in all aspects. The results showed that our analysis had great potential in explaining the EET mechanism.