title: Specific, sensitive, high-resolution detection of protein molecules in eukaryotic cells using metal-tagging transmission electron microscopy.
abstract: More than any other methodology, transmission electron microscopy (TEM) has contributed to our understanding of the architecture and organization of cells. With current detection limits approaching atomic resolution, it will ultimately become possible to ultrastructurally image intracellular macromolecular assemblies in situ. Presently, however, methods to unambiguously identify proteins within the crowded environment of the cell's interior are lagging behind. We describe an approach, metal-tagging TEM (METTEM), that allows detection of intracellular proteins in mammalian cells with high specificity, exceptional sensitivity, and at molecular scale resolution. In live cells treated with gold salts, proteins bearing a small metal-binding tag will form 1-nm gold nanoclusters, readily detectable in electron micrographs. The applicability and strength of METTEM is demonstrated by a study of Rubella virus replicase and capsid proteins, which revealed virus-induced cell structures not seen before.
authors.affiliation: Cell Structure Lab, Centro Nacional de Biotecnología/CSIC, Darwin 3, Campus de Cantoblanco, 28049 Madrid, Spain. crisco@cnb.csic.es
authors.forename: Cristina
authors.initials: C
authors.lastname: Risco
authors.forename: Eva
authors.initials: E
authors.lastname: Sanmartín-Conesa
authors.forename: Wen-Pin
authors.initials: WP
authors.lastname: Tzeng
authors.forename: Teryl K
authors.initials: TK
authors.lastname: Frey
authors.forename: Volker
authors.initials: V
authors.lastname: Seybold
authors.forename: Raoul J
authors.initials: RJ
authors.lastname: de Groot
mesh_terms: D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D002478:Cells, Cultured; D022082:Cellular Structures / Q000648:ultrastructure; D005057:Eukaryotic Cells / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008668:Metallothionein / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D008670:Metals / Q000737:chemistry* / Q000378:metabolism; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D008856:Microscopy, Fluorescence; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000648:ultrastructure; D012412:Rubella virus / Q000201:enzymology / Q000378:metabolism; D012680:Sensitivity and Specificity; D014764:Viral Proteins / Q000737:chemistry
chemical_list: D036022:Capsid Proteins; D008670:Metals; D011506:Proteins; D014764:Viral Proteins; D006046:Gold; D008668:Metallothionein