The structure of a mycobacterial outer-membrane channel
Michael Faller1, Michael Niederweis, Georg E Schulz
1Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany.
Science (New York, N.Y.)
|February 21, 2004
Summary
The first structure of Mycobacterium smegmatis porin A (MspA) reveals a unique goblet shape. This finding offers new insights into how nutrients cross the resistant mycobacterial outer membrane.
Area of Science:
- Structural biology
- Microbiology
- Biochemistry
Background:
- Mycobacteria possess highly impermeable outer membranes, contributing to their resistance against antibiotics.
- Transmembrane channel proteins, known as porins, facilitate the passage of hydrophilic nutrients across these membranes.
Purpose of the Study:
- To determine the three-dimensional structure of the primary porin, MspA, from Mycobacterium smegmatis.
- To elucidate the structural basis for nutrient transport across the mycobacterial outer membrane.
Main Methods:
- X-ray crystallography was employed to analyze the MspA protein.
- Structural analysis was performed using the Protein Data Bank.
Main Results:
- The structure of MspA was determined, revealing a homooctameric, goblet-like conformation with a single central channel.
- This represents the first reported structure of a mycobacterial outer membrane protein.
- MspA features two consecutive beta barrels with nonpolar outer surfaces, forming a ribbon structure.
Conclusions:
- The determined MspA structure provides novel insights into the architecture of mycobacterial outer membrane proteins.
- The unique structural features of MspA may explain its role in nutrient transport despite its narrow conformation relative to current models of the mycobacterial outer membrane.
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