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Updated: Jul 7, 2026
09:55
From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins
Published on: July 4, 2016
Atomic-level models of the bacterial carboxysome shell.
Shiho Tanaka1, Cheryl A Kerfeld, Michael R Sawaya
1Department of Chemistry and Biochemistry, University of California at Los Angeles (UCLA), Los Angeles, CA 90095, USA.
Science (New York, N.Y.)
|February 23, 2008
Summary
Researchers elucidated the atomic structures of two key carboxysome shell proteins, CcmL and OrfA. These pentameric proteins, along with known hexamers, form plausible models for the bacterial microcompartment shell involved in carbon fixation.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Carboxysomes are bacterial microcompartments crucial for carbon fixation.
- Their polyhedral shells are assembled from thousands of protein subunits.
- Previous research detailed the structure of hexameric shell proteins.
Purpose of the Study:
- To determine the three-dimensional structures of CcmL and OrfA proteins.
- To understand the role of these proteins in carboxysome shell assembly.
- To build preliminary atomic models of the carboxysome shell.
Main Methods:
- X-ray crystallography was used to determine protein structures.
- High-resolution structural data (2.4 and 2.15 angstroms) was obtained.
- Structural data was integrated with existing knowledge of hexameric proteins.
Main Results:
- The structures of CcmL and OrfA were resolved at high resolution.
- Both proteins were found to form pentameric structures.
- These pentamers are compatible with forming the vertices of an icosahedral shell.
Conclusions:
- CcmL and OrfA are essential pentameric building blocks of the carboxysome shell.
- The findings enable the construction of preliminary atomic models for the carboxysome shell.
- This work advances our understanding of bacterial carbon fixation machinery.
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