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Titolo:
A comprehensive characterization of a group IB intron and its encoded maturase reveals that protein-assisted splicing requires an almost intact intron RNA
Autore:
Geese, WJ; Waring, RB;
Indirizzi:
Temple Univ, Dept Biol, Philadelphia, PA 19122 USA Temple Univ Philadelphia PA USA 19122 pt Biol, Philadelphia, PA 19122 USA
Titolo Testata:
JOURNAL OF MOLECULAR BIOLOGY
fascicolo: 4, volume: 308, anno: 2001,
pagine: 609 - 622
SICI:
0022-2836(20010511)308:4<609:ACCOAG>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOBILE GENETIC ELEMENTS; IN-VITRO SELECTION; CRYSTAL-STRUCTURE; TETRAHYMENA RIBOZYME; ASPERGILLUS-NIDULANS; HOMING ENDONUCLEASE; TERTIARY STRUCTURE; CATALYTIC CORE; STACKED HELICES; BINDING;
Keywords:
catalytic RNA; group I intron; homing endonuclease; RNA binding protein; RNA folding;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Waring, RB Temple Univ, Dept Biol, Philadelphia, PA 19122 USA Temple UnivPhiladelphia PA USA 19122 iladelphia, PA 19122 USA
Citazione:
W.J. Geese e R.B. Waring, "A comprehensive characterization of a group IB intron and its encoded maturase reveals that protein-assisted splicing requires an almost intact intron RNA", J MOL BIOL, 308(4), 2001, pp. 609-622

Abstract

The group I intron (AnCOB) of the mitochondrial apocytochrome b gene from Aspergillus nidulans encodes a bi-functional maturase protein that is also a DNA endonuclease. Although the AnCOB intron self-splices, the encoded maturase protein greatly facilitates splicing, in part, by stabilizing RNA tertiary structure. To determine their role in self-splicing and in protein-assisted splicing, several peripheral RNA sub-domains in the 313 nucleotide intron were deleted (P2, P9, P9.1) or truncated (P5ab, P6a). The sequence intwo helices (P2 and P9) was also inverted. Except for P9, the deleted regions are not highly conserved among group I introns and are often dispensable for catalytic activity. Nevertheless, despite the very tight binding of AnCOB RNA to the maturase and the high activity of the bimolecular complex (the rate of 5 ' splice-site cleavage was > 20 min(-1) with guanosine as thecofactor), the intron was surprisingly sensitive to these modifications. Several mutations inactivated splicing completely and virtually all impairedsplicing to varying degrees. Mutants containing comparatively small deletions in various regions of the intron significantly decreased binding affinity (generally > 10(4)-fold), indicating that none of the domains that remained constitutes the primary recognition site of the maturase. The data argue that tight binding requires tertiary interactions that can be maintained by only a relatively intact intron RNA, and that the binding mechanism of the maturase differs from those of two other well-characterized group I intron splicing factors, CYT-18 and Cpb2. A model is proposed in which the protein promotes widespread cooperative folding of an RNA lacking extensive initial tertiary structure. (C) 2001 Academic Press.

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Documento generato il 29/03/20 alle ore 09:13:49