Crystals of MscSCrystals of MscSCrystals of MscS

Mitochondria and actin collide

Image and article by Dr. Magnus S. Alphey, University of St. Andrews

These crystals are grown from recombinant MscS protein. The protein is overexpressed in lab strains of E. coli cultured in Formedium LB broth supplemented with antibiotics. The recombinant MscS protein is purified away from the cocktail of endogenous E. coli proteins using column chromatography.

The heptameric mechanosensitive channel of small conductance (MscS) provides a critical function in Escherichia coli where it opens in response to increased bilayer tension. It constitutes an integral inner-membrane protein which acts as a safety valve and protects the cell against extreme hypoosmotic conditions.

Legend: MscS in the open form. Side and top views of the channel pore. 2Fo-Fc electron density map of the transmembrane helices of a single MscS chain contoured at 1.5σ (golden chicken wire).

PDB code: 4AGE

Pliotas, Christos, Richard Ward, Emma Branigan, Akiko Rasmussen, Gregor Hagelueken, Hexian Huang, Susan S Black, Ian R Booth, Olav Schiemann, and James H Naismith. “Conformational State of the MscS Mechanosensitive Channel in Solution Revealed by Pulsed Electron – Electron Double Resonance ( PELDOR ) Spectroscopy.” Proceedings of the National Academy of Sciences of the United States of America 109, no. 40 (2012): 2675-82. doi:10.1073/pnas.1202286109.