Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
J Proteome Res. 2013 Sep 6;12(9):3952-68. doi: 10.1021/pr400245k. Epub 2013 Aug 27.
Lysine acetylation in proteins has recently been globally identified in bacteria and eukaryotes. Even though acetylproteins are known to be involved in various cellular processes, its physiological significance has not yet been resolved. Using a proteomics approach in combination with immunoprecipitation, we identified 197 lysine acetylation sites and 4 N-terminal acetylation sites from 128 proteins in Thermus thermophilus HB8, an extremely thermophilic eubacterium. Our analyses revealed that identified acetylproteins are well conserved across all three domains of life and are mainly involved in central metabolism and translation. To characterize the functional significance further, we successfully mapped 172 acetylation sites on their 59 authentic and 54 homologous protein structures. Although the percentage of acetylation on ordered structures was higher than that of the disordered structure, no tendency of acetylation in T. thermophilus was detected in secondary structures. However, the acetylated lysine was situated near the negatively charged glutamic acid residues. In tertiary structure analyses, 58 sites of 103 acetylations mapped on 59 authentic structures of T. thermophilus were located within a considerable distance that can disrupt electrostatic interactions and hydrogen bonding networks on protein surfaces, demonstrating the physiological significance of the acetylation that can directly alter the protein structure. In addition, we found 16 acetylation sites related to Schiff base formation, ligand binding, and protein-RNA and protein-protein interactions that involve the potential function of the proteins. The structural mapping of acetylation sites provides new molecular insight into the role of lysine acetylation in the proteins.
蛋白质中的赖氨酸乙酰化最近在细菌和真核生物中被全局鉴定。尽管乙酰化蛋白已知参与各种细胞过程，但它的生理意义尚未解决。我们使用蛋白质组学方法结合免疫沉淀，从极端嗜热真细菌 Thermus thermophilus HB8 中鉴定了 128 种蛋白质中的 197 个赖氨酸乙酰化位点和 4 个 N 端乙酰化位点。我们的分析表明，鉴定出的乙酰化蛋白在所有三个生命领域都得到很好的保守，主要参与中心代谢和翻译。为了进一步表征其功能意义，我们成功地将 172 个乙酰化位点映射到其 59 个真实和 54 个同源蛋白结构上。尽管有序结构上的乙酰化百分比高于无序结构，但在二级结构中未检测到 Thermus thermophilus 的乙酰化趋势。然而，乙酰化的赖氨酸位于带负电荷的谷氨酸残基附近。在三级结构分析中，103 个乙酰化中的 58 个位点映射到 Thermus thermophilus 的 59 个真实结构上，位于相当大的距离内，可以破坏蛋白质表面的静电相互作用和氢键网络，表明乙酰化可以直接改变蛋白质结构，具有生理意义。此外，我们发现了 16 个与席夫碱形成、配体结合以及蛋白质-RNA 和蛋白质-蛋白质相互作用相关的乙酰化位点，涉及到蛋白质的潜在功能。乙酰化位点的结构映射为赖氨酸乙酰化在蛋白质中的作用提供了新的分子见解。
