Gomes Ricardo A, Vicente Miranda Hugo, Silva Marta Sousa, Graça Gonçalo, Coelho Ana V, Ferreira António E, Cordeiro Carlos, Freire Ana Ponces
Centro de Química e Bioquímica, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Portugal.
FEBS J. 2006 Dec;273(23):5273-87. doi: 10.1111/j.1742-4658.2006.05520.x. Epub 2006 Oct 25.
Protein glycation by methylglyoxal is a nonenzymatic post-translational modification whereby arginine and lysine side chains form a chemically heterogeneous group of advanced glycation end-products. Methylglyoxal-derived advanced glycation end-products are involved in pathologies such as diabetes and neurodegenerative diseases of the amyloid type. As methylglyoxal is produced nonenzymatically from dihydroxyacetone phosphate and d-glyceraldehyde 3-phosphate during glycolysis, its formation occurs in all living cells. Understanding methylglyoxal glycation in model systems will provide important clues regarding glycation prevention in higher organisms in the context of widespread human diseases. Using Saccharomyces cerevisiae cells with different glycation phenotypes and MALDI-TOF peptide mass fingerprints, we identified enolase 2 as the primary methylglyoxal glycation target in yeast. Two other glycolytic enzymes are also glycated, aldolase and phosphoglycerate mutase. Despite enolase's activity loss, in a glycation-dependent way, glycolytic flux and glycerol production remained unchanged. None of these enzymes has any effect on glycolytic flux, as evaluated by sensitivity analysis, showing that yeast glycolysis is a very robust metabolic pathway. Three heat shock proteins are also glycated, Hsp71/72 and Hsp26. For all glycated proteins, the nature and molecular location of some advanced glycation end-products were determined by MALDI-TOF. Yeast cells experienced selective pressure towards efficient use of d-glucose, with high methylglyoxal formation as a side effect. Glycation is a fact of life for these cells, and some glycolytic enzymes could be deployed to contain methylglyoxal that evades its enzymatic catabolism. Heat shock proteins may be involved in proteolytic processing (Hsp71/72) or protein salvaging (Hsp26).
甲基乙二醛引起的蛋白质糖基化是一种非酶促翻译后修饰，精氨酸和赖氨酸侧链会形成一组化学性质各异的晚期糖基化终产物。甲基乙二醛衍生的晚期糖基化终产物与糖尿病和淀粉样变性神经退行性疾病等病理状况有关。由于甲基乙二醛是在糖酵解过程中由磷酸二羟丙酮和3-磷酸d-甘油醛非酶促产生的，其形成发生在所有活细胞中。了解模型系统中的甲基乙二醛糖基化将为在广泛的人类疾病背景下预防高等生物中的糖基化提供重要线索。利用具有不同糖基化表型的酿酒酵母细胞和基质辅助激光解吸电离飞行时间肽质量指纹图谱，我们确定烯醇酶2是酵母中主要的甲基乙二醛糖基化靶点。另外两种糖酵解酶也会发生糖基化，即醛缩酶和磷酸甘油酸变位酶。尽管烯醇酶的活性以糖基化依赖的方式丧失，但糖酵解通量和甘油产量保持不变。通过敏感性分析评估，这些酶均未对糖酵解通量产生任何影响，表明酵母糖酵解是一条非常稳健的代谢途径。三种热休克蛋白也会发生糖基化，即Hsp71/72和Hsp26。对于所有糖基化蛋白，一些晚期糖基化终产物的性质和分子位置通过基质辅助激光解吸电离飞行时间质谱法确定。酵母细胞在高效利用d-葡萄糖方面面临选择性压力，同时会产生大量甲基乙二醛作为副作用。糖基化是这些细胞生活中的一个事实，一些糖酵解酶可能被用于控制逃避其酶促分解代谢的甲基乙二醛。热休克蛋白可能参与蛋白水解加工（Hsp71/72）或蛋白质挽救（Hsp26）。
