期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：24
页码：13815-13820
DOI：10.1073/pnas.2336221100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Two proteins are encoded by the mammalian retrotransposon long interspersed nuclear element 1 (LINE-1 or L1); both are essential for retrotransposition. The function of the protein encoded by the 5'-most ORF, ORF1p, is incompletely understood, although the ORF1p from mouse L1 is known to bind single-stranded nucleic acids and function as a nucleic acid chaperone. ORF1p self-associates by means of a long coiled-coil domain in the N-terminal region of the protein, and the basic, C-terminal region (C-1/3 domain) contains the nucleic acid binding activity. The full-length and C-1/3 domains of ORF1p were purified to near homogeneity then analyzed by gel filtration chromatography and analytical ultracentrifugation. Both proteins were structurally homogeneous and asymmetric in solution, with the full-length version forming a stable trimer and the C-1/3 domain remaining a monomer. Examination of the full-length protein by atomic force microscopy revealed an asymmetric dumbbell shape, congruent with the chromatography and ultracentrifugation results. These structural features are compatible with the nucleic acid binding and chaperone activities of L1 ORF1p and offer further insight into the functions of this unique protein during LINE-1 retrotransposition.
