Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo 062-8517, Japan.
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Japan.
Int J Mol Sci. 2021 Mar 31;22(7):3637. doi: 10.3390/ijms22073637.
Beetle hyperactive antifreeze protein (AFP) has a unique ability to maintain a supercooling state of its body fluids, however, less is known about its origination. Here, we found that a popular stag beetle () synthesizes at least 6 isoforms of hyperactive AFP (AFP). Cold-acclimated larvae tolerated -5 °C chilled storage for 24 h and fully recovered after warming, suggesting that AFP facilitates overwintering of this beetle. A AFP isoform (~10 kDa) appeared to consist of 6-8 tandem repeats of a 12-residue consensus sequence (TCTxSxNCxxAx), which exhibited 3 °C of high freezing point depression and the ability of binding to an entire surface of a single ice crystal. Significantly, these properties as well as DNA sequences including the untranslated region, signal peptide region, and an AFP-encoding region of are highly similar to those identified for a known hyperactive AFP (AFP) from the beetle (). Progenitor of and was branched off approximately 300 million years ago, so no known evolution mechanism hardly explains the retainment of the DNA sequence for such a lo-ng divergence period. Existence of unrevealed gene transfer mechanism will be hypothesized between these two phylogenetically distant beetles to acquire this type of hyperactive AFP.
甲虫抗冻活性蛋白 (AFP) 具有维持体液过冷状态的独特能力，但关于其起源的了解较少。在这里，我们发现一种受欢迎的鹿角甲虫 () 至少合成了 6 种 AFP 的同工型 (AFP)。经过冷驯化的幼虫能够耐受 -5°C 的冷藏 24 小时，并且在升温后完全恢复，这表明 AFP 有助于这种甲虫的越冬。一种 AFP 同工型（~10 kDa）似乎由 6-8 个串联重复的 12 个残基保守序列 (TCTxSxNCxxAx) 组成，该序列表现出 3°C 的高冰点降低和结合单个冰晶整个表面的能力。重要的是，这些特性以及包括未翻译区、信号肽区和 AFP 编码区在内的 DNA 序列与已知的甲虫 AFP 的那些特性非常相似 ()。和的祖先大约在 3 亿年前分支出来，因此，几乎没有已知的进化机制可以解释如此长时间的 DNA 序列保留。我们将假设这两种系统发育上相距较远的甲虫之间存在尚未揭示的基因转移机制，以获得这种类型的 AFP。
