Newman S M, Eannetta N T, Yu H, Prince J P, de Vicente M C, Tanksley S D, Steffens J C
Department of Plant Breeding and Biometry, Cornell University, Ithaca, NY 14853-1902.
Plant Mol Biol. 1993 Mar;21(6):1035-51. doi: 10.1007/BF00023601.
We report the isolation and characterization of seven nuclear genes encoding polyphenol oxidase (PPO) in tomato (Lycopersicon esculentum cv. VFNT Cherry). The seven genes (PPOs A, A', B, C, D, E and F) fall into three structural classes (I, II, and III) based on Eco RI and Hind III restriction fragment length polymorphisms (RFLP). RFLP mapping and PFGE analysis demonstrated that the genes reside on chromosome 8, and may be clustered within a 165 kb region. Phage insert mapping demonstrated PPO E and PPO F (both class III), and PPOs B, D and A (classes I, II and I respectively) are grouped within separate 12.4 kb clusters. The complete nucleotide sequence was determined for each gene. Comparison to cDNAs revealed that the PPOs lack introns. A transcript of about 2 kb is expected for each PPO. Each PPO possesses a region encoding a transit peptide characteristic of polypeptides targeted to the thylakoid lumen. Predicted precursor polypeptides range in mass from 66 to 71 kDa and predicted mature polypeptides range from 57 to 62 kDa. All the PPOs encode two putative copper-binding sites characteristic of bacterial, fungal and mammalian tyrosinases. Five of the seven PPOs possess divergent DNA sequences in their 5' promoter regions. These flanking sequence differences may regulate the differential expression of PPO genes.
我们报道了从番茄（Lycopersicon esculentum cv. VFNT Cherry）中分离并鉴定出7个编码多酚氧化酶（PPO）的核基因。基于Eco RI和Hind III限制性片段长度多态性（RFLP），这7个基因（PPOs A、A'、B、C、D、E和F）可分为三个结构类（I、II和III）。RFLP图谱分析和脉冲场凝胶电泳（PFGE）分析表明，这些基因位于8号染色体上，并且可能聚集在一个165 kb的区域内。噬菌体插入图谱显示，PPO E和PPO F（均为III类）以及PPOs B、D和A（分别为I、II和I类）分别聚集在单独的12.4 kb簇中。测定了每个基因的完整核苷酸序列。与cDNA的比较显示，PPOs没有内含子。预计每个PPO有一个约2 kb的转录本。每个PPO都有一个编码转运肽的区域，该转运肽是靶向类囊体腔的多肽所特有的。预测的前体多肽质量范围为66至71 kDa，预测的成熟多肽质量范围为57至62 kDa。所有PPOs都编码两个假定的铜结合位点，这是细菌、真菌和哺乳动物酪氨酸酶所特有的。7个PPOs中的5个在其5'启动子区域具有不同的DNA序列。这些侧翼序列差异可能调节PPO基因的差异表达。
