The L-L oligomerization domain resides at the very N-terminus of the sendai virus L RNA polymerase protein.
The Sendai virus RNA-dependent RNA polymerase is composed of the L and P proteins. We previously showed that the L protein gives intragenic complementation and forms an oligomer where the L-L interaction site mapped to the N-terminal half of the protein (S. Smallwood et al., 2002, Virology, 00, 000-000). We now show that L oligomerization does not depend on P protein and progressively smaller N-terminal fragments of L from amino acids (aa) 1-1146 through aa 1-174 all bind wild-type L. C-terminal truncations up to aa 424, which bind L, can complement the transcription defect in an L mutant altered at aa 379, although these L truncation mutants do not bind P. The fragment of L comprising aa 1-895, furthermore, acts as a dominant-negative mutant to inhibit transcription of wild-type L. N-terminal deletions of aa 1-189 and aa 1-734 have lost the ability to form the L-L complex as well as the L-P complex, although they still bind C protein. These data are consistent with the L-L interaction site residing in aa 1-174. Site-directed mutations in the N-terminal 347 aa, of L which abolish P binding, do not affect L-L complex formation, so while the L and P binding sites on L are overlapping they are mediated by different amino acids. The N-terminal portions of L with aa 1-424, aa 1-381, and to a lesser extent aa 1-174, can complement the transcription defect in an L mutant altered at aa 77-81, showing their L-L interaction is functional.
Cevik
Bayram
B
Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville 32610-0266, USA.
Smallwood
Sherin
S
Moyer
Sue A
SA
D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry / Q000378:metabolism*; D029082:Sendai virus / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D010750:Phosphoproteins; D014764:Viral Proteins; C064365:L protein, Sendai virus; D012324:RNA-Dependent RNA Polymerase; D012321:DNA-Directed RNA Polymerases