Regulation and functions of polyphenol oxidases (PPOs) in the moss Physcomitrella

多酚氧化酶（PPO）是几乎普遍存在的酶，它将多酚氧化成高活性的醌。PPO的确切生物学功能知之甚少。我们的小组在苔藓小立碗藓中鉴定出了第一个bratite PPO基因，该基因与高等植物PPO有一些相似之处，但也有一些差异。的立碗藓PPO 1基因的衍生氨基酸序列的分析以及酶学研究揭示了一个强大的膜协会。该项目利用立碗藓作为模式植物的优势，重点研究：（a）利用过表达和基因敲除的方法对PPO进行功能研究;（B）PPO在转录和酶活性水平上的调节实验;（c）研究酶特性的方法，如亚细胞定位和底物特异性。将鉴定立碗藓中作为潜在PPO底物的主要酚类化合物的化学结构。我们假设，阐明PPO功能立碗藓作为一种早期的陆地植物，可以大大有助于了解这种几乎无处不在的酶的生理和进化作用。

Polyphenol oxidases (PPOs) are almost ubiquitous enzymes, which oxidise polyphenols to highly reactive quinones. The exact biological function of PPOs is poorly understood. Our group identified the first bryophyte PPO gene in the moss Physcomitrella patens with several similarities but also differences to higher plant PPOs. Analysis of the derived amino acid sequence of the Physcomitrella PPO1 gene as well as enzymological studies revealed a strong membrane association. Transcription of PPO1 was shown to vary in the time course of a culture.The project uses the advantages of Physcomitrella as a model plant and focuses on: (a) functional studies on PPO using approaches of overexpression and gene knockout; (b) experiments on regulation of PPO on the levels of transcription and enzyme activity; (c) approaches to investigate enzyme properties such as subcellular localisation and substrate specificity. The chemical structure of the major phenolic compounds from Physcomitrella as potential PPO substrates will be identified. We assume that an elucidation of PPO functions in Physcomitrella as an early land plant can substantially help to understand the physiological and evolutionary role of this almost ubiquitous enzyme.