Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Scienvaces, National Taiwan University, Taipei, Taiwan.
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
Toxicon. 2021 Jul 30;198:93-101. doi: 10.1016/j.toxicon.2021.04.022. Epub 2021 May 3.
The semi-fossil and pit-less Azemiops feae is possibly the most primitive crotalid species. Here, we have cloned and sequenced cDNAs encoding four serine proteases (vSPs) from the venom glands of Chinese A. feae. Full amino-acid sequences of the major vSP (designated as AzKNa) and three minor vSPs (designated as AzKNb, AzKNc and Az-PA) were deduced. Using Protein-BLAST search, the ten most-similar vSPs for each Azemiops vSP have been selected for multiple sequence alignment, and all the homologs are crotalid vSPs. The results suggest that the A. feae vSPs are structurally most like those of eastern-Chinese Gloydius, Viridovipera, Protobothrops and North American pitvipers, and quite different from more-specialized vSPs such as Agkistrodon venom Protein-C activators. The vSPs from Chinese A. feae and those from Vietnamese A. feae show significant sequence variations. AzKNa is acidic and contains six potential N-glycosylation sites and its surface-charge distribution differs greatly from that of AzKNb, as revealed by 3D-modeling. AzKNb and AzKNc do not contain N-glycosylation sites although most of their close homologs contain one or two. Az-PA belongs to the plasminogen-activator subtype with a conserved N-glycosylation site. The evolution of this subtype of vSPs in Azemiops and related pitvipers has been traced by phylogenetic analysis.
半化石无坑的 Azemiops feae 可能是最原始的响尾蛇物种。在这里，我们从中国 A. feae 的毒腺中克隆并测序了编码四种丝氨酸蛋白酶 (vSP) 的 cDNA。主要 vSP（命名为 AzKNa）和三种次要 vSP（命名为 AzKNb、AzKNc 和 Az-PA）的全长氨基酸序列被推断出来。使用 Protein-BLAST 搜索，为每个 Azemiops vSP 选择了十个最相似的 vSP 进行多序列比对，所有同源物都是响尾蛇 vSP。结果表明，A. feae vSP 在结构上与中国东部的 Gloydius、Viridovipera、Protobothrops 和北美的响尾蛇最为相似，而与更专业化的 vSP（如 Agkistrodon 毒液蛋白 C 激活剂）则截然不同。来自中国 A. feae 和越南 A. feae 的 vSP 显示出显著的序列变异。AzKNa 是酸性的，含有六个潜在的 N-糖基化位点，其表面电荷分布与 AzKNb 有很大差异，这是通过 3D 建模揭示的。AzKNb 和 AzKNc 不含 N-糖基化位点，尽管它们的大多数近亲含有一个或两个。Az-PA 属于纤溶酶原激活剂亚型，含有保守的 N-糖基化位点。通过系统发育分析追踪了 Azemiops 和相关响尾蛇中这种 vSP 亚型的进化。
