Silica cell walls of diatoms have attracted attention as a source of nanostructured functional materials and have immense potential for a variety of applications. Previous studies of silica cell wall formation have identified numerous involved proteins, but most of these proteins are species-specific and are not conserved among diatoms. However, because the basic process of diatom cell wall formation is common to all diatom species, ubiquitous proteins and molecules will reveal the mechanisms of cell wall formation. In this study, we assembled de novo transcriptomes of three diatom species, Nitzschia palea, Achnanthes kuwaitensis, and Pseudoleyanella lunata, and compared protein-coding genes of five genome-sequenced diatom species. These analyses revealed a number of diatom-specific genes that encode putative endoplasmic reticulum-targeting proteins. Significant numbers of these proteins showed homology to silicanin-1, which is a conserved diatom protein that reportedly contributes to cell wall formation. These proteins also included a previously unrecognized SET domain protein methyltransferase family that may regulate functions of cell wall formation-related proteins and long-chain polyamines. Proteomic analysis of cell wall-associated proteins in N. palea identified a protein that is also encoded by one of the diatom-specific genes. Expression analysis showed that candidate genes were upregulated in response to silicon, suggesting that these genes play roles in silica cell wall formation. These candidate genes can facilitate further investigations of silica cell wall formation in diatoms.

中文翻译：

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专注于二氧化硅细胞壁形成的比较基因分析：硅藻特异性 SET 结构域蛋白甲基转移酶的鉴定。

硅藻的二氧化硅细胞壁作为纳米结构功能材料的来源引起了人们的注意，并且在各种应用中具有巨大的潜力。以前对二氧化硅细胞壁形成的研究已经确定了许多涉及的蛋白质，但这些蛋白质中的大多数是物种特异性的，并且在硅藻中并不保守。然而，由于硅藻细胞壁形成的基本过程是所有硅藻物种共有的，无处不在的蛋白质和分子将揭示细胞壁形成的机制。在这项研究中，我们组装的从头转录三种硅藻种，菱形内稃，曲壳藻kuwaitensis和Pseudoleyanella霉，并比较了五种基因组测序的硅藻物种的蛋白质编码基因。这些分析揭示了许多硅藻特异性基因，这些基因编码假定的内质网靶向蛋白。大量这些蛋白质显示出与siliconin-1 的同源性，siliconin-1 是一种保守的硅藻蛋白，据报道有助于细胞壁形成。这些蛋白质还包括一个以前未被认识的 SET 域蛋白质甲基转移酶家族，它可以调节细胞壁形成相关蛋白质和长链多胺的功能。N. palea细胞壁相关蛋白的蛋白质组学分析鉴定了一种蛋白质，该蛋白质也由硅藻特异性基因之一编码。表达分析显示候选基因响应于硅而上调，表明这些基因在硅细胞壁形成中起作用。这些候选基因可以促进对硅藻中二氧化硅细胞壁形成的进一步研究。