Rubicon is a potent negative regulator of autophagy and a potential target for autophagy-inducing therapeutics. Rubicon-mediated inhibition of autophagy requires the interaction of the C-terminal Rubicon homology (RH) domain of Rubicon with Rab7–GTP. Here we report the 2.8-Å crystal structure of the Rubicon RH domain in complex with Rab7–GTP. Our structure reveals a fold for the RH domain built around four zinc clusters. The switch regions of Rab7 insert into pockets on the surface of the RH domain in a mode that is distinct from those of other Rab–effector complexes. Rubicon residues at the dimer interface are required for Rubicon and Rab7 to colocalize in living cells. Mutation of Rubicon RH residues in the Rab7-binding site restores efficient autophagic flux in the presence of overexpressed Rubicon, validating the Rubicon RH domain as a promising therapeutic target.

Rubicon是有效的自噬负调节剂，也是自噬诱导疗法的潜在靶标。Rubicon介导的自噬抑制作用需要Rubicon的C末端Rubicon同源（RH）域与Rab7–GTP相互作用。在这里，我们报告了与Rab7–GTP复合的Rubicon RH域的2.8-Å晶体结构。我们的结构揭示了围绕四个锌簇构建的RH域的折叠。Rab7的开关区域以不同于其他Rab-效应复合物的模式插入RH域表面的口袋中。Rubicon和Rab7在活细胞中共定位需要二聚体界面处的Rubicon残基。在存在过表达的Rubicon的情况下，Rab7结合位点中Rubicon RH残基的突变可恢复有效的自噬通量，