Biology Department, Zhangzhou Normal University, 36 Xian Qian Zhi Street, Zhangzhou 363000, Fujian, China.
Biochem Genet. 2013 Jun;51(5-6):413-25. doi: 10.1007/s10528-013-9574-0. Epub 2013 Feb 12.
L-gulono-gamma-lactone oxidase (GULO) catalyzes the final step in vertebrate vitamin C biosynthesis. Vitamin C-incapable vertebrates lack the GULO gene. Gene structure and phylogenetic analyses showed that vertebrate GULO genes are 64-95% identical at the amino acid level and consist of 11 conserved exons. GULO pseudogenes have multiple indel mutations and premature stop codons in higher primates, guinea pigs, and some bats. No GULO-like sequences were identified in teleost fishes. During animal GULO evolution, exon F was subdivided into F1 and F2. Additional GULO retropseudogenes were identified in dogs, cats, and giant pandas. GULO-flanking genome regions acquired frequent segment translocations and inversions during vertebrate evolution. Purifying selection was detected across vertebrate GULO genes (d(N)/d(S) = 0.069), except for some positively selected sites identified in sharks and frogs. These positive sites demonstrated little functional significance when mapped onto the three-dimensional GULO protein structure. Vertebrate GULO genes are conserved except for those that are lost.
L-古洛糖酸-γ-内酯氧化酶（GULO）催化脊椎动物维生素 C 生物合成的最后一步。缺乏 GULO 基因的维生素 C 无能脊椎动物。基因结构和系统发育分析表明，脊椎动物 GULO 基因在氨基酸水平上具有 64-95%的同一性，由 11 个保守外显子组成。在高等灵长类动物、豚鼠和某些蝙蝠中，GULO 假基因具有多个插入/缺失突变和提前终止密码子。在硬骨鱼类中未鉴定出类似 GULO 的序列。在动物 GULO 进化过程中，外显子 F 被细分为 F1 和 F2。在狗、猫和大熊猫中还鉴定出了额外的 GULO 反转假基因。在脊椎动物进化过程中，GULO 侧翼基因组区域发生了频繁的片段易位和倒位。除了在鲨鱼和青蛙中鉴定出的一些正选择位点外，在整个脊椎动物 GULO 基因中检测到纯化选择（d（N）/d（S）= 0.069）。这些正选择位点映射到三维 GULO 蛋白质结构上时，显示出很少的功能意义。脊椎动物 GULO 基因是保守的，除了那些丢失的基因。
