ジャーナル: Sci Rep / 年: 2016 タイトル: Fusion to a homo-oligomeric scaffold allows cryo-EM analysis of a small protein. 著者: Francesca Coscia / Leandro F Estrozi / Fabienne Hans / Hélène Malet / Marjolaine Noirclerc-Savoye / Guy Schoehn / Carlo Petosa / 要旨: Recent technical advances have revolutionized the field of cryo-electron microscopy (cryo-EM). However, most monomeric proteins remain too small (<100 kDa) for cryo-EM analysis. To overcome this limitation, we explored a strategy whereby a monomeric target protein is genetically fused to a homo-oligomeric scaffold protein and the junction optimized to allow the target to adopt the scaffold symmetry, thereby generating a chimeric particle suitable for cryo-EM. To demonstrate the concept, we fused maltose-binding protein (MBP), a 40 kDa monomer, to glutamine synthetase, a dodecamer formed by two hexameric rings. Chimeric constructs with different junction lengths were screened by biophysical analysis and negative-stain EM. The optimal construct yielded a cryo-EM reconstruction that revealed the MBP structure at sub-nanometre resolution. These findings illustrate the feasibility of using homo-oligomeric scaffolds to enable cryo-EM analysis of monomeric proteins, paving the way for applying this strategy to challenging structures resistant to crystallographic and NMR analysis.
モデルのタイプ: OTHER 詳細: Reference models were generated by angular reconstitution using IMAGIC and volumes refined by projection matching using SPIDER. As a control to check for possible model bias, we generated an ...詳細: Reference models were generated by angular reconstitution using IMAGIC and volumes refined by projection matching using SPIDER. As a control to check for possible model bias, we generated an alternative ab initio reference model using RIco, which uses symmetry adapted functions.