MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
Structure. 2013 Jun 4;21(6):1051-8. doi: 10.1016/j.str.2013.03.013. Epub 2013 May 9.
Rhomboids are evolutionarily conserved serine proteases that cleave transmembrane proteins within the membrane. The increasing number of known rhomboid functions in prokaryotes and eukaryotes makes them attractive drug targets. Here, we describe structures of the Escherichia coli rhomboid GlpG in complex with β-lactam inhibitors. The inhibitors form a single bond to the catalytic serine and the carbonyl oxygen of the inhibitor faces away from the oxyanion hole. The hydrophobic N-substituent of β-lactam inhibitors points into a cavity within the enzyme, providing a structural explanation for the specificity of β-lactams on rhomboid proteases. This same cavity probably represents the S2' substrate binding site of GlpG. We suggest that the structural changes in β-lactam inhibitor binding reflect the state of the enzyme at an initial stage of substrate binding to the active site. The structural insights from these enzyme-inhibitor complexes provide a starting point for structure-based design for rhomboid inhibitors.
菱形蛋白酶是进化上保守的丝氨酸蛋白酶，能够在膜内切割跨膜蛋白。越来越多的原核生物和真核生物中已知的菱形蛋白酶功能使它们成为有吸引力的药物靶点。在这里，我们描述了大肠杆菌菱形蛋白酶 GlpG 与β-内酰胺抑制剂复合物的结构。抑制剂与催化丝氨酸形成单键，抑制剂的羰基氧远离氧阴离子穴。β-内酰胺抑制剂的疏水性 N-取代基指向酶内的一个腔，为β-内酰胺对菱形蛋白酶的特异性提供了结构解释。这个相同的腔可能代表 GlpG 的 S2' 底物结合位点。我们认为，β-内酰胺抑制剂结合的结构变化反映了酶在底物与活性位点初始结合阶段的状态。这些酶-抑制剂复合物的结构见解为基于结构的菱形蛋白酶抑制剂设计提供了起点。
