Structures of the Prokaryotic Mechanosensitive Channels MscL and MscS

• Published in: Current Topics in Membranes Vol. 58; pp. 1 - 24
• Main Authors: Steinbacher, Stefan, Bass, Randal, Strop, Pavel, Rees, Douglas C.
• Format: Book Chapter
• Language: English
• Published: United States Elsevier Science & Technology 2007
• Subjects: Biochemistry; Cellular biology; Molecular biology
• ISBN: 9780121533588; 0121533581
• ISSN: 1063-5823
• DOI: 10.1016/S1063-5823(06)58001-9

This chapter describes the crystallographic analyses of the Mycobacterium tuberculosis mechanosensitive channels of large (MscL) and the Escherichia coli mechanosensitive channels of small (MscS). Crystal structures of the M. tuberculosis MscL and E. coli MscS were initially reported at 3.5‐ and 3.9‐ Å resolutions, respectively. The basic structural framework of the MscL and MscS transmembrane domains is provided by α‐helices; each subunit of MscL has two helices for a total of 10, whereas MscS has three helices per subunit for a total of 21. From a structural perspective, MscL and MscS represent fascinating targets as they provide an opportunity to explore the coupling between protein conformation and the membrane environment responsible for channel gating. Tension and pressure sensitive systems, such as MscL and MscS, have the attraction that these environmental properties are energetically coupled to changes in protein area and volume, respectively that may be directly quantitated from structural models.