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Structure of the in vitro assembled bacteriophage phi6 polymerase complexStructure of the in vitro assembled bacteriophage phi6 polymerase complex
Structural highlights
FunctionP1_BPPH6 P1 is the major inner capsid (core) protein of the polyhedral procapsid, which is responsible for genomic replication and transcription. Forms a dodecahedral shell from 60 asymmetric dimers. Binds to RNA and may be involved in genomic packaging. Publication Abstract from PubMedElectron cryomicroscopy can yield near-atomic resolution structures of highly ordered macromolecular complexes. Often however some subunits bind in a flexible manner, have different symmetry from the rest of the complex, or are present in sub-stoichiometric amounts, limiting the attainable resolution. Here we report a general method for the localized three-dimensional reconstruction of such subunits. After determining the particle orientations, local areas corresponding to the subunits can be extracted and treated as single particles. We demonstrate the method using three examples including a flexible assembly and complexes harbouring subunits with either partial occupancy or mismatched symmetry. Most notably, the method allows accurate fitting of the monomeric RNA-dependent RNA polymerase bound at the threefold axis of symmetry inside a viral capsid, revealing for the first time its exact orientation and interactions with the capsid proteins. Localized reconstruction is expected to provide novel biological insights in a range of challenging biological systems. Localized reconstruction of subunits from electron cryomicroscopy images of macromolecular complexes.,Ilca SL, Kotecha A, Sun X, Poranen MM, Stuart DI, Huiskonen JT Nat Commun. 2015 Nov 4;6:8843. doi: 10.1038/ncomms9843. PMID:26534841[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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