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Related Experiment Video

Updated: Jul 18, 2026

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

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Structural basis for intramembrane proteolysis by rhomboid serine proteases.

Adam Ben-Shem¹, Deborah Fass, Eitan Bibi

¹Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel. adam.ben-shem@weizmann.ac.il

Proceedings of the National Academy of Sciences of the United States of America

|December 28, 2006

Summary

We determined the crystal structure of an E. coli rhomboid, revealing a unique active site cavity. This structure explains how these intramembrane proteases function within the cell membrane.

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Area of Science:

Biochemistry
Structural Biology
Membrane Biology

Background:

Intramembrane proteases cleave peptide bonds within integral membrane proteins.
This activity is vital for numerous biological and pathological processes.
Rhomboids are a widespread family of intramembrane serine proteases.

Purpose of the Study:

To elucidate the structural basis of rhomboid protease function.
To understand the mechanism of intramembrane proteolysis.
To investigate substrate access to the active site.

Main Methods:

X-ray crystallography
Determination of the 2.3-Å resolution crystal structure of an *Escherichia coli* rhomboid.

Main Results:

The structure reveals six transmembrane helices, with five surrounding a short TM4 helix.
The catalytic serine residue is located within an externally exposed, hydrophilic cavity.
This cavity facilitates water-dependent catalysis within the hydrophobic membrane environment.

Conclusions:

The rhomboid active site is structured to enable catalysis deep within the membrane.
The findings suggest a mechanism for substrate access to the sequestered active site.
This work provides insights into the function of intramembrane serine proteases.