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Substrate binding and specificity of rhomboid intramembrane protease revealed by substrate–peptide complex structures
Author(s) -
Zoll Sebastian,
Stanchev Stancho,
Began Jakub,
Škerle Jan,
Lepšík Martin,
Peclinovská Lucie,
Majer Pavel,
Strisovsky Kvido
Publication year - 2014
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201489367
Subject(s) - rhomboid , proteases , biology , protease , protein superfamily , binding site , substrate (aquarium) , biochemistry , protein structure , active site , enzyme , gene , ecology
The mechanisms of intramembrane proteases are incompletely understood due to the lack of structural data on substrate complexes. To gain insight into substrate binding by rhomboid proteases, we have synthesised a series of novel peptidyl‐chloromethylketone ( CMK ) inhibitors and analysed their interactions with Escherichia coli rhomboid GlpG enzymologically and structurally. We show that peptidyl‐ CMK s derived from the natural rhomboid substrate TatA from bacterium Providencia stuartii bind GlpG in a substrate‐like manner, and their co‐crystal structures with GlpG reveal the S1 to S4 subsites of the protease. The S1 subsite is prominent and merges into the ‘water retention site’, suggesting intimate interplay between substrate binding, specificity and catalysis. Unexpectedly, the S4 subsite is plastically formed by residues of the L1 loop, an important but hitherto enigmatic feature of the rhomboid fold. We propose that the homologous region of members of the wider rhomboid‐like protein superfamily may have similar substrate or client‐protein binding function. Finally, using molecular dynamics, we generate a model of the Michaelis complex of the substrate bound in the active site of GlpG.