对土地的征服给植物带来了严重的问题,他们必须通过适应生物合成能力来应对。适应紫外线照射,失水,病原体和草食动物的防御,地球的拉力是必不可少的。缓解这些问题的化合物可以通过苯丙素途径合成,其核心是三种酶:苯丙氨酸解氨酶(PAL),肉桂酸4-羟化酶,和4-香豆酸辅酶A-连接酶(4CL)。模型生物的基因组,Charabraunii作为水生藻类和两种苔藓植物Physcomitriumpatens和Marchantiapolymorpha,搜索编码PAL和4CL的序列,并选择在大肠杆菌中异源表达的序列进行生化表征。在多晶型Marchantia和Physcomitriumpatens中,两种酶都鉴定了几种可能的同工型,而Charabraunii只能检索到一个或两个同工型。这两种酶的活性形式都存在于所有三种生物体中,尽管催化效率在很大范围内变化。l-苯丙氨酸被所有PAL类酶接受为最佳底物,尽管在某些情况下注释暗示了不同的活动。4CL的底物光谱更加多样化,但咖啡酸和/或4-香豆酸通常是最佳接受的底物。我们的调查显示PAL和4CL,形成酚类化合物的重要酶,作为征服土地的模式生物,在现存的木结构植物和苔藓植物中存在并活跃。
The conquest of land posed severe problems to plants which they had to cope with by adapting biosynthetic capacities. Adaptations to respond to UV irradiation, water loss, pathogen and herbivore defense, and the earth\'s pull were essential. Chemical compounds alleviating these problems can be synthesized by the phenylpropanoid pathway, the core of which are three enzymes: phenylalanine ammonia-lyase (PAL), cinnamic acid 4-hydroxylase, and 4-coumaric acid coenzyme A-ligase (4CL). The genomes of model organisms, Chara braunii as aquatic alga and the two bryophytes Physcomitrium patens and Marchantia polymorpha, were searched for sequences encoding PAL and 4CL and selected sequences heterologously expressed in Escherichia coli for biochemical characterization. Several possible isoforms were identified for both enzymes in Marchantia polymorpha and Physcomitrium patens, while only one or two isoforms could be retrieved for Chara braunii. Active forms of both enzymes were found in all three organisms, although the catalytic efficiencies varied in a wide range. l-Phenylalanine was accepted as best substrate by all PAL-like enzymes, despite annotations in some cases suggesting different activities. The substrate spectrum of 4CLs was more diverse, but caffeic and/or 4-coumaric acids generally were the best-accepted substrates. Our investigations show that PAL and 4CL, important enzymes for the formation of phenolic compounds, are present and active in extant charophytes and bryophytes as model organisms for the conquest of land.