Turchetto-Zolet Andreia Carina, Margis-Pinheiro Marcia, Margis Rogerio
Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Mol Genet Genomics. 2009 Jan;281(1):87-97. doi: 10.1007/s00438-008-0396-4. Epub 2008 Nov 12.
Many plants synthesize and accumulate proline in response to osmotic stress conditions. A central enzyme in the proline biosynthesis is the bifunctional enzyme Delta(1)-pyrroline-5-carboxylate synthase (P5CS) that includes two functional catalytic domains: the gamma-glutamyl kinase and the glutamic-gamma-semialdehyde dehydrogenase. This enzyme catalyzes the first two steps of the proline biosynthetic pathway and plays a central role in the regulation of this process in plants. To determine the evolutionary events that occurred in P5CS genes, partial sequences from four Neotropical trees were cloned and compared to those of other plant taxa. Molecular phylogenetic analysis indicated that P5CS duplication events have occurred several times following the emergence of flowering plants and at different frequencies throughout the evolution of monocots and dicots. Despite the high number of conserved residues in plant P5CS sequences, positive selection was observed at different regions of P5CS paralogous genes and also when dicots and monocots were contrasted.
许多植物在渗透胁迫条件下会合成并积累脯氨酸。脯氨酸生物合成中的一种关键酶是双功能酶Δ¹-吡咯啉-5-羧酸合成酶（P5CS），它包含两个功能催化结构域：γ-谷氨酰激酶和谷氨酸-γ-半醛脱氢酶。该酶催化脯氨酸生物合成途径的前两个步骤，并在植物这一过程的调控中起核心作用。为了确定P5CS基因中发生的进化事件，克隆了四种新热带树木的部分序列，并与其他植物类群的序列进行了比较。分子系统发育分析表明，P5CS基因复制事件在开花植物出现后发生了多次，并且在单子叶植物和双子叶植物的整个进化过程中以不同频率发生。尽管植物P5CS序列中有大量保守残基，但在P5CS旁系同源基因的不同区域以及对比双子叶植物和单子叶植物时都观察到了正选择。
