赭曲霉全基因组测序和功能注释及其重要次级代谢产物生物合成基因簇的预测

发布时间：2018-03-26 22:16

本文选题：赭曲霉菌　切入点：赭曲霉素A　出处：《南方医科大学》2017年博士论文

【摘要】：Aspergillus westerdijkiae(赭曲霉)是隶属于曲霉属环绕组的一种丝状真菌。该霉菌因其产生的主要次级代谢产物——赭曲霉毒素A(ochratoxin A,OTA)具有强烈的肝脏和肾脏毒性以及潜在的致癌和致突变能力而受到全世界的广泛关注。研究发现,在玉米、小麦等粮食或饲料以及咖啡、啤酒和果汁饮料等食品产品中都能检测到A.westerdijkiae的存在及OTA的污染,严重危害人类健康及家畜安全。作为丝状真菌家族的一员,A.westerdijkiae的酶催化作用和次级代谢产物生物合成能力在工业生产和医药卫生领域也有极大的开发潜力。为了揭示A.westerdijkiae的病原性、潜在的酶降解能力以及其重要次级代谢产物OTA的生物合成机制,我们对A.westerdijkiae进行了全基因组测序和功能注释,并与其它8个已公开全基因组测序数据的曲霉属物种进行了全基因组比较分析。本研究中,我们测序和组装了大约36 MB的A.westerdijkiae基因组序列,并预测出10861个蛋白质编码基因。我们对A.westerdijkiae和其它8个曲霉属物种全基因组范围的单拷贝直系同源基因构建了系统发生树,发现A.oryzae和A.flavus在进化上和A.westerdijkiae更相近。这两个相似物种可以为A.westerdijkiae基因组的功能注释提供更多有效的参考序列。随后,我们在10861个蛋白质编码基因中预测到716个细胞色素P450酶编码基因,663个碳水化合物活性酶编码基因以及377个蛋白水解酶编码基因。基于比较基因组学分析、KEGG注释以及结构域预测,我们在663个碳水化合物活性酶编码基因中进一步筛选出了 288个植物多糖降解酶编码基因。在A.westerdijkiae基因组中我们还预测到大量次级代谢产物生物合成基因簇,说明A.westerdijkiae具有显著的次级代谢产物生产能力。通过进一步的结构域预测、功能注释以及比较基因组学分析,我们成功预测到两个与OTA生物合成相关的基因簇(cluster37和cluster69),并详细注释了基因簇中所有的重要元件。我们发现基因簇cluster69中的两相邻GH3和AA3家族碳水化合物水解酶编码基因很可能是导致A.westerdijkize在不同基质中OTA生物合成能力差异的主要原因。本研究首次对A.westerdijk aj进行了全基因组测序和全面的生物信息学分析,并报道了其重要次级产物OTA的生物合成基因簇。这将为今后研究如何控制OTA的污染起到指导性的作用。此外,我们还对A.westerdijkiae碳水化合物降解和蛋白水解能力进行了分析,并预测了大量潜在的与菌体的宿主入侵以及病原性相关蛋白的编码基因,为揭示A.westerdijkia示的生物特性及其与环境相互作用的机制供了极其丰富且有价值的数据资源。
[Abstract]:Aspergillus westerdijkiaeis a filamentous fungus belonging to the group of Aspergillus. The fungus has strong liver and kidney toxicity and potential carcinogenic and protuberance due to its main secondary metabolite, ochratoxin A(ochratoxin. The ability to change has attracted worldwide attention. The presence of A.westerdijkiae and the contamination of OTA can be detected in food or feed such as corn and wheat, as well as in food products such as coffee, beer and juice drinks. As a member of the filamentous fungi family, A. westerdijkiae has great potential for enzyme catalysis and secondary metabolites biosynthesis in the field of industrial production and medicine and health. The potential enzyme degradation ability and the biosynthesis mechanism of OTA, an important secondary metabolite of A.westerdijkiae, were sequenced and explained. In this study, we sequenced and assembled about 36 MB of A.westerdijkiae genome sequence. 10861 protein coding genes were predicted. Phylogenetic tree was constructed for A.westerdijkiae and 8 other genome-wide homologous genes of single copy lineage of Aspergillus species. It was found that A.oryzae and A.flavus were evolutionarily closer to A.westerdijkiae. These two similar species could provide more useful reference sequences for functional annotation of A.westerdijkiae genomes. We predicted 716 cytochrome P450 enzyme coding genes, 663 carbohydrate active enzyme coding genes and 377 protein hydrolase coding genes in 10861 protein coding genes. We further screened 288 plant polysaccharide-degrading enzyme coding genes from 663 carbohydrate active enzyme coding genes. We also predicted a large number of secondary metabolites biosynthesis gene clusters in the A.westerdijkiae genome. A.westerdijkiae has significant secondary metabolite productivity. Further domain prediction, functional annotation and comparative genomics analysis, We successfully predicted two clusters of genes related to OTA biosynthesis, including cluster 37 and cluster 69, and explained in detail all the important elements in the cluster. We found that the carbohydrate hydrolase codes of two adjacent GH3 and AA3 families in the gene cluster cluster69 are encoded. Gene may be the main reason for the difference of OTA biosynthesis ability of A.westerdijkize in different substrates. In this study, A.westerdijk AJ was sequenced for the first time, and a comprehensive bioinformatics analysis was carried out. The biosynthesis gene cluster of OTA, an important secondary product of A.westerdijkiae, is reported, which will play a guiding role in the future study on how to control the pollution of OTA. In addition, we also analyze the ability of carbohydrate degradation and protein hydrolysis of A.westerdijkiae. A large number of potential genes encoding host invasion and pathogenicity related proteins were predicted, which provided valuable data resources for revealing the biological characteristics of A.westerdijkia and the mechanism of its interaction with the environment.
【学位授予单位】：南方医科大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：Q93

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