Isolation and electron microscopic characterization of the high molecular mass aminoacyl-tRNA synthetase complex from murine erythroleukemia cells.
A high molecular mass aminoacyl-tRNA synthetase complex has been isolated from a murine erythroleukemia cell line. This multienzyme complex contains activities for the arginyl-, aspartyl-, glutamyl-, glutaminyl-, isoleucyl,- leucyl-, lysyl-, methionyl-, and prolyl-tRNA synthetases. This enzyme composition, the polypeptide pattern observed upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the relative stoichiometry of the component polypeptides are characteristic of high molecular mass complexes of aminoacyl-tRNA synthetases isolated from a variety of mammalian tissues and cell types. Negatively stained preparations of native complex and of glutaraldehyde-treated material have been examined by electron microscopy. In both cases, a distinctive particle is observed which appears in several orientations. The most common views are of two different projections of a squarish particle that measures approximately 27 x 27 nm. Other commonly observed views are of a "U" shape, a rectangle, and a triangle. All of these views are seen in both gradient-purified samples and those prepared directly from material as isolated. These data are consistent with a model for the multienzyme aminoacyl-tRNA synthetase complex as a "cup" or elongated U structure. These studies demonstrate that the high molecular mass complex of eukaryotic aminoacyl-tRNA synthetases does have a coherent structure that can be visualized by electron microscopy.
Norcum
M T
MT
Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.
D000604:Amino Acyl-tRNA Synthetases / Q000302:isolation & purification*; D000818:Animals; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D005990:Glycerol; D004915:Leukemia, Erythroblastic, Acute / Q000201:enzymology*; D046911:Macromolecular Substances; D051379:Mice; D008854:Microscopy, Electron / Q000379:methods; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification*; D014407:Tumor Cells, Cultured / Q000201:enzymology* / Q000648:ultrastructure
D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D000604:Amino Acyl-tRNA Synthetases; D005990:Glycerol