Single-Particle Cryo-EM: A rising star in structural biology
Date:
Monday, January 16, 2017 08:45 - 09:45
Speaker:
Doreen Matthies (National Institutes of Health (NIH))
Location:
Mondi Seminar Room 2, Central Building
Series:
Life Sciences Seminar
Contact:
DEL REAL LAVERGNE Pedro
Cryo-EM is currently revolutionizing the field of structural biology. Due to recent advances in detector technologies, hardware & software improvements, this method is becoming more and more mainstream in solving high-resolution structures. It complements methods such as X-ray crystallography & NMR spectroscopy with the advantage of not having to form well-ordered crystals or having an upper size limit. Progress in the field of single-particle cryo-EM will be discussed with examples of soluble & membrane protein complexes yielding resolutions of better than 3 Å. A study on 200 kDa Mg2+ channel CorA will be used as a detailed example. CorA is a homo-pentamer and is gated by intracellular Mg2+. We determined the structures of CorA in the presence and absence of Mg2+ using single-particle cryo-EM. The five-fold symmetric Mg2+-bound closed state of CorA at an overall 3.8 Å resolution reveals side-chain densities as well as densities for several magnesium ions. Cryo-EM of Mg2+-free open state CorA revealed dramatic differences in the conformation of the channel with large asymmetric changes in the soluble domain of the pentameric complex suggesting an unprecedented gating mechanism.