Department of Organismal Biology, Uppsala University, Sweden.
School of Natural Sciences, University of California Merced.
Genome Biol Evol. 2020 Jul 1;12(7):993-1012. doi: 10.1093/gbe/evz274.
Glycosaminoglycans are sulfated polysaccharide molecules, essential for many biological processes. The 6-O sulfation of glycosaminoglycans is carried out by carbohydrate 6-O sulfotransferases (C6OSTs), previously named Gal/GalNAc/GlcNAc 6-O sulfotransferases. Here, for the first time, we present a detailed phylogenetic reconstruction, analysis of gene synteny conservation and propose an evolutionary scenario for the C6OST family in major vertebrate groups, including mammals, birds, nonavian reptiles, amphibians, lobe-finned fishes, ray-finned fishes, cartilaginous fishes, and jawless vertebrates. The C6OST gene expansion likely started early in the chordate lineage, giving rise to four ancestral genes after the divergence of tunicates and before the emergence of extant vertebrates. The two rounds of whole-genome duplication in early vertebrate evolution (1R/2R) only contributed two additional C6OST subtype genes, increasing the vertebrate repertoire from four genes to six, divided into two branches. The first branch includes CHST1 and CHST3 as well as a previously unrecognized subtype, CHST16 that was lost in amniotes. The second branch includes CHST2, CHST7, and CHST5. Subsequently, local duplications of CHST5 gave rise to CHST4 in the ancestor of tetrapods, and to CHST6 in the ancestor of primates. The teleost-specific gene duplicates were identified for CHST1, CHST2, and CHST3 and are result of whole-genome duplication (3R) in the teleost lineage. We could also detect multiple, more recent lineage-specific duplicates. Thus, the vertebrate repertoire of C6OST genes has been shaped by gene duplications and gene losses at several stages of vertebrate evolution, with implications for the evolution of skeleton, nervous system, and cell-cell interactions.
糖胺聚糖是硫酸化多糖分子，对许多生物过程至关重要。糖胺聚糖的 6-O 硫酸化由碳水化合物 6-O 硫酸转移酶（C6OST）完成，这些酶之前被命名为 Gal/GalNAc/GlcNAc 6-O 硫酸转移酶。在这里，我们首次进行了详细的系统发育重建、基因同线性保守性分析，并提出了 C6OST 家族在主要脊椎动物群中的进化情景，包括哺乳动物、鸟类、非鸟类爬行动物、两栖动物、有尾两栖类、有鳍鱼类、软骨鱼类和无颌脊椎动物。C6OST 基因的扩张可能在脊索动物进化的早期就开始了，在被囊动物和现存脊椎动物出现之前，有 4 个祖先基因发生了分歧。脊椎动物早期进化中的两次全基因组复制（1R/2R）仅贡献了另外两个 C6OST 亚型基因，使脊椎动物的基因库从 4 个基因增加到 6 个，分为两个分支。第一个分支包括 CHST1 和 CHST3 以及之前未被识别的亚型 CHST16，该亚型在羊膜动物中丢失。第二个分支包括 CHST2、CHST7 和 CHST5。随后，CHST5 在四足动物祖先中的局部重复产生了 CHST4，而在灵长类动物祖先中则产生了 CHST6。硬骨鱼特有的基因重复是由于硬骨鱼谱系中的全基因组复制（3R）产生的，在 CHST1、CHST2 和 CHST3 中都有发现。我们还可以检测到多个更近的谱系特异性重复。因此，脊椎动物 C6OST 基因库的形成是由脊椎动物进化过程中的基因复制和基因丢失造成的，这对骨骼、神经系统和细胞-细胞相互作用的进化有影响。
