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Curr Opin Struct Biol. 2016 Oct;40:120-127. doi: 10.1016/j.sbi.2016.09.009. Epub 2016 Sep 30.

Cryo-EM in the study of challenging systems: the human transcription pre-initiation complex.

Author information

1
Molecular and Cell Biology Department and QB3 Institute, UC Berkeley, CA, USA; Howard Hughes Medical Institute, UC Berkeley, CA, USA; Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Lab, CA, USA. Electronic address: enogales@lbl.gov.
2
Biophysics Graduate Group, UC Berkeley, CA, USA.
3
Department of Molecular Biosciences, Northwestern University, IL, USA.

Abstract

Single particle cryo-Electron Microscopy (cryo-EM) is a technique that allows the structural characterization of macromolecules without the need for crystallization. For certain type of samples that are ideally suited for cryo-EM studies it has been possible to reach high-resolution structures following relatively standard procedures. Other biological systems remain highly challenging, even for cryo-EM. Challenges may involve the scarcity of the sample, poor stability of the complexes, and most often, the intrinsic flexibility of biological molecules. Among these challenging samples are large eukaryotic transcription complexes, which suffer from all such shortcomings. Here we report how we have recently tried to overcome those challenges in order to improve our structural understanding of the human transcription pre-initiation complex assembly and the transcription initiation process. Parallel efforts have also been carried out for budding yeast transcription initiation complexes, allowing comparisons that establish both the overall conservation and the specific structural differences between the two systems.

PMID:
27689812
PMCID:
PMC5161697
DOI:
10.1016/j.sbi.2016.09.009
[Indexed for MEDLINE]
Free PMC Article

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