Structure of the core editing complex (L-complex) involved in uridine insertion/deletion RNA editing in trypanosomatid mitochondria.
Uridine insertion/deletion RNA editing is a unique form of posttranscriptional RNA processing that occurs in mitochondria of kinetoplastid protists. We have carried out 3D structural analyses of the core editing complex or "L (ligase)-complex" from Leishmania tarentolae mitochondria isolated by the tandem affinity purification procedure (TAP). The purified material, sedimented at 20-25S, migrated in a blue native gel at 1 MDa and exhibited both precleaved and full-cycle gRNA-mediated U-insertion and U-deletion in vitro activities. The purified L-complex was analyzed by electron tomography to determine the extent of heterogeneity. Three-dimensional structural comparisons of individual particles in the tomograms revealed that a majority of the complexes have a similar shape of a slender triangle. An independent single-particle reconstruction, using a featureless Gaussian ball as the initial model, converged to a similar triangular structure. Another single-particle reconstruction, using the averaged tomography structure as the initial model, yielded a similar structure. The REL1 ligase was localized on the model to the base of the apex by decoration with REL1-specific IgG. This structure should prove useful for a detailed analysis of the editing reaction.
Li
Feng
F
Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.
Ge
Peng
P
Hui
Wong H
WH
Atanasov
Ivo
I
Rogers
Kestrel
K
Guo
Qiang
Q
Osato
Daren
D
Falick
Arnold M
AM
Zhou
Z Hong
ZH
Simpson
Larry
L
D000818:Animals; D015153:Blotting, Western; D019729:Carbon-Oxygen Ligases / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D055032:Electron Microscope Tomography; D007891:Leishmania / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D008958:Models, Molecular; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D017393:RNA Editing; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D014529:Uridine / Q000235:genetics* / Q000378:metabolism
D024101:Mitochondrial Proteins; D015800:Protozoan Proteins; D016053:RNA, Protozoan; D019729:Carbon-Oxygen Ligases; D014529:Uridine