Structure and Mechanism of Rhomboid Protease

Yoshinori Akiyama,Yi Xue,Ya Ha

doi:10.1074/jbc.r112.422378

Yoshinori Akiyama, Yi Xue + Show 1 more

Open Access

https://doi.org/10.1074/jbc.r112.422378

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Abstract

Rhomboid protease was first discovered in Drosophila. Mutation of the fly gene interfered with growth factor signaling and produced a characteristic phenotype of a pointed head skeleton. The name rhomboid has since been widely used to describe a large family of related membrane proteins that have diverse biological functions but share a common catalytic core domain composed of six membrane-spanning segments. Most rhomboid proteases cleave membrane protein substrates near the N terminus of their transmembrane domains. How these proteases function within the confines of the membrane is not completely understood. Recent progress in crystallographic analysis of the Escherichia coli rhomboid protease GlpG in complex with inhibitors has provided new insights into the catalytic mechanism of the protease and its conformational change. Improved biochemical assays have also identified a substrate sequence motif that is specifically recognized by many rhomboid proteases.

Highlights

The Drosophila growth factor Spitz is synthesized with a C-terminal transmembrane (TM)3 domain that anchors it to the endoplasmic reticulum membrane
Cleavage of the TM domain by rhomboid protease is required for the release of Spitz into solution, which enables it to diffuse and bind to EGF receptors (EGFRs) in signal-receiving cells [1]
Crystallographic analyses revealed the fold of the membrane protein and showed that the HxxxN motif in S2 (His-150; Asn-154 in the E. coli protease), the GxSG motif near the N terminus of S4 (Ser-201), and the (A/G)H motif in S6 (His-254) are all essential elements of the active site of the enzyme

Summary

Structure and Mechanism of Rhomboid Protease*

Ya Ha‡1, Yoshinori Akiyama§2, and Yi Xue‡ From the ‡Department of Pharmacology, Yale School of Medicine, New Haven, Connecticut 06520 and the §Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan. Most rhomboid proteases cleave membrane protein substrates near the N terminus of their transmembrane domains. Besides the basic 6-TM configuration represented by E. coli GlpG, some rhomboid proteases, e.g. the mitochondrial rhomboid PARL and Drosophila Rhomboid-1, have an additional TM helix outside the core domain toward either the N terminus (1 ϩ 6) or the C terminus (6 ϩ 1) of the protein [4] Their structures are not yet known, the 7-TM versions of the protease are expected to share the same basic catalytic mechanism

Catalytic Mechanism and Inhibitor Binding

Conformational Change in the Protease and Substrate

Substrate Specificity

Future Prospects