Max-Planck-Institute of Molecular Plant Physiology, 14476, Potsdam, Germany.
B CUBE Center for Molecular Bioengineering, TU Dresden, 01307, Dresden, Germany.
Plant J. 2022 Jun;110(6):1700-1716. doi: 10.1111/tpj.15765. Epub 2022 Apr 26.
Morphogenesis of the intricate patterns of diatom silica cell walls is a protein-guided process, yet to date only very few such silica biomineralization proteins have been identified. Therefore, it is currently unknown whether all diatoms share conserved proteins of a basal silica forming machinery, and whether unique proteins are responsible for the morphogenesis of species-specific silica patterns. To answer these questions, we extracted proteins from the silica of three diatom species (Thalassiosira pseudonana, Thalassiosira oceanica, and Cyclotella cryptica) by complete demineralization of the cell walls. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis of the extracts identified 92 proteins that we name 'soluble silicome proteins' (SSPs). Surprisingly, no SSPs are common to all three species, and most SSPs showed very low similarity to one another in sequence alignments. In-depth bioinformatics analyses revealed that SSPs could be grouped into distinct classes based on short unconventional sequence motifs whose functions are yet unknown. The results from the in vivo localization of selected SSPs indicates that proteins, which lack sequence homology but share unconventional sequence motifs may exert similar functions in the morphogenesis of the diatom silica cell wall.
硅藻二氧化硅细胞壁复杂图案的形态发生是一个蛋白质引导的过程，但迄今为止，只有极少数这样的硅质生物矿化蛋白被鉴定出来。因此，目前尚不清楚所有硅藻是否都具有基本的硅质形成机制的保守蛋白，以及是否有独特的蛋白负责物种特异性硅质图案的形态发生。为了回答这些问题，我们通过完全脱矿化细胞壁从三种硅藻（拟菱形藻、大洋藻和隐藻）的二氧化硅中提取蛋白质。对提取物进行的液相色谱-串联质谱（LC-MS/MS）分析鉴定出 92 种我们称之为“可溶性硅质蛋白”（SSP）的蛋白。令人惊讶的是，没有一种 SSP 是所有三种物种共有的，而且大多数 SSP 在序列比对中彼此之间的相似度非常低。深入的生物信息学分析表明，SSP 可以根据其功能未知的短非常规序列基序分为不同的类别。对选定 SSP 的体内定位的结果表明，缺乏序列同源性但具有非常规序列基序的蛋白质可能在硅藻二氧化硅细胞壁的形态发生中发挥相似的功能。
