Hans Elmlund
Academic Appointments
- Postdoctoral Research fellow, Structural Biology
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- Academic Offices
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Scientific Focus
Current Research Interests
My primary research focus is on development of general 3D reconstruction methodology for high-resolution single-particle cryo-electron microscopy, free from dependency on a priori available structural information, assumptions about particle symmetry, or tilted data collection in negative stain. I want to provide a technological platform that enables low-dose cryo data collection in one step, followed by automated 3D reconstruction of all structural states in the single-particle ensemble. The collection of algorithms developed so far constitutes a new open source software packageĀSIMPLE (Single-particle IMage Processing Linux Engine). SIMPLE is an easy-to-use image processing system for semi-automated ab initio 3D reconstruction from challenging single-particle data sets, involving asymmetrical and structurally heterogeneous particles. Concurrently, I am working with applying my methods to solve structures of large transcription regulatory complexes. Using cryo-EM structure determination in combination with supporting biochemical techniques, I want to establish structure-function relationships for the general transcription factors in the initiation process. Working together with Roger Kornberg and colleagues, I have determined the structure of the yeast pre-initiation complex, containing RNA polymerase II (pol II), TBP, TFIIA, TFIIB, TFIIE, TFIIF, and TFIIH, assembled on double-stranded DNA. Impending work will focus on characterization of the structural rearrangements that are required for melting of the promoter DNA, entry of single-stranded DNA into the active site cleft of pol II, and transition into active elongation. The long-term objective is to increase the complexity of this picture by adding additional major players, such as Mediator and TFIID. I hope that my work will open up new horizons for single-particle techniques in structural biology and provide the structural basis for the mechanism of transcription regulation. Download my program package SIMPLE at: http://simple.stanford.edu.
Publications
- SIMPLE: Software for ab initio reconstruction of heterogeneous single-particles. J Struct Biol. 2012; (3): 420-7
- The activity of barley NADPH-dependent thioredoxin reductase C is independent of the oligomeric state of the protein: tetrameric structure determined by cryo-electron microscopy. Biochemistry. 2011; (18): 3713-23
- ATP-induced conformational dynamics in the AAA+ motor unit of magnesium chelatase. Structure. 2010; (3): 354-65
- Ab initio structure determination from electron microscopic images of single molecules coexisting in different functional states. Structure. 2010; (7): 777-86
- Cryo-EM reveals promoter DNA binding and conformational flexibility of the general transcription factor TFIID. Structure. 2009; (11): 1442-52
- High-resolution single-particle orientation refinement based on spectrally self-adapting common lines. J Struct Biol. 2009; (1): 83-94
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