Okanishi Hiroki, Kim Kwang, Masui Ryoji, Kuramitsu Seiki
From the *Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
From the *Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
Mol Cell Proteomics. 2014 Sep;13(9):2382-98. doi: 10.1074/mcp.M113.035659. Epub 2014 Jun 17.
Recent studies of protein post-translational modifications revealed that various types of lysine acylation occur in eukaryotic and bacterial proteins. Lysine propionylation, a newly discovered type of acylation, occurs in several proteins, including some histones. In this study, we identified 361 propionylation sites in 183 mid-exponential phase and late stationary phase proteins from Thermus thermophilus HB8, an extremely thermophilic eubacterium. Functional classification of the propionylproteins revealed that the number of propionylation sites in metabolic enzymes increased in late stationary phase, irrespective of protein abundance. The propionylation sites on proteins expressed in mid-exponential and late stationary phases partially overlapped. Furthermore, amino acid frequencies in the vicinity of propionylation sites differed, not only between the two growth phases but also relative to acetylation sites. In addition, 33.8% of mid-exponential phase-specific and 80.0% of late stationary phase-specific propionylations (n ≥ 2) implied that specific mechanisms regulate propionylation in the cell. Moreover, the limited degree of overlap between lysine propionylation (36.8%) and acetylation (49.2%) sites in 67 proteins that were both acetylated and propionylated strongly suggested that the two acylation reactions are regulated separately by specific enzymes and may serve different functions. Finally, we also found that eight propionylation sites overlapped with acetylation sites critical for protein functions such as Schiff-base formation and ligand binding.
近期关于蛋白质翻译后修饰的研究表明，真核生物和细菌蛋白质中存在多种类型的赖氨酸酰化修饰。赖氨酸丙酰化是一种新发现的酰化类型，存在于多种蛋白质中，包括一些组蛋白。在本研究中，我们在嗜热栖热菌HB8（一种极端嗜热的真细菌）的183种指数中期和稳定期末期蛋白质中鉴定出361个丙酰化位点。对丙酰化蛋白质的功能分类显示，代谢酶中丙酰化位点的数量在稳定期末期增加，与蛋白质丰度无关。指数中期和稳定期末期表达的蛋白质上的丙酰化位点部分重叠。此外，丙酰化位点附近的氨基酸频率不仅在两个生长阶段有所不同，相对于乙酰化位点也存在差异。此外，33.8%的指数中期特异性丙酰化和80.0%的稳定期末期特异性丙酰化（n≥2）表明细胞中存在特定机制调节丙酰化。此外，在67种既被乙酰化又被丙酰化的蛋白质中，赖氨酸丙酰化（36.8%）和乙酰化（49.2%）位点之间的重叠程度有限，这强烈表明这两种酰化反应由特定酶分别调节，可能具有不同功能。最后，我们还发现8个丙酰化位点与对蛋白质功能（如席夫碱形成和配体结合）至关重要的乙酰化位点重叠。
