Department of Ecology and Evolutionary Biology, University of California, Los Angeles, USA.
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, USA.
Sci Rep. 2020 Nov 10;10(1):19407. doi: 10.1038/s41598-020-75846-4.
Here we report the first recovery, sequencing, and identification of fossil biomineral proteins from a Pleistocene fossil invertebrate, the stony coral Orbicella annularis. This fossil retains total hydrolysable amino acids of a roughly similar composition to extracts from modern O. annularis skeletons, with the amino acid data rich in Asx (Asp + Asn) and Glx (Glu + Gln) typical of invertebrate skeletal proteins. It also retains several proteins, including a highly acidic protein, also known from modern coral skeletal proteomes that we sequenced by LC-MS/MS over multiple trials in the best-preserved fossil coral specimen. A combination of degradation or amino acid racemization inhibition of trypsin digestion appears to limit greater recovery. Nevertheless, our workflow determines optimal samples for effective sequencing of fossil coral proteins, allowing comparison of modern and fossil invertebrate protein sequences, and will likely lead to further improvements of the methods. Sequencing of endogenous organic molecules in fossil invertebrate biominerals provides an ancient record of composition, potentially clarifying evolutionary changes and biotic responses to paleoenvironments.
在这里，我们报告了首例从更新世无脊椎动物石珊瑚（Orbicella annularis）化石中回收、测序和鉴定化石生物矿化蛋白的研究。该化石保留了总水解氨基酸，其组成与现代 O. annularis 骨骼提取物大致相似，且氨基酸数据富含天冬氨酸（Asp+Asn）和谷氨酸（Glu+Gln），这是典型的无脊椎动物骨骼蛋白特征。它还保留了几种蛋白质，包括一种高度酸性的蛋白质，这种蛋白质也存在于我们通过 LC-MS/MS 在保存最完好的化石珊瑚标本上进行的多次试验中测序得到的现代珊瑚骨骼蛋白质组中。胰蛋白酶消化过程中降解或氨基酸外消旋抑制的组合似乎限制了更大程度的回收。尽管如此，我们的工作流程确定了用于有效测序化石珊瑚蛋白的最佳样本，允许比较现代和化石无脊椎动物的蛋白质序列，并可能进一步改进这些方法。在化石无脊椎动物生物矿化物中对内源性有机分子进行测序，提供了组成的古老记录，可能有助于阐明进化变化和生物对古环境的响应。
