Requirements for mini-exon inclusion in potato invertase mRNAs provides evidence for exon-scanning interactions in plants.
RNA
; 6(3): 422-33, 2000 Mar.
Article
em En
| MEDLINE
| ID: mdl-10744026
ABSTRACT
Invertases are responsible for the breakdown of sucrose to fructose and glucose. In all but one plant invertase gene, the second exon is only 9 nt in length and encodes three amino acids of a five-amino-acid sequence that is highly conserved in all invertases of plant origin. Sequences responsible for normal splicing (inclusion) of exon 2 have been investigated in vivo using the potato invertase, invGF gene. The upstream intron 1 is required for inclusion whereas the downstream intron 2 is not. Mutations within intron 1 have identified two sequence elements that are needed for inclusion a putative branchpoint sequence and an adjacent U-rich region. Both are recognized plant intron splicing signals. The branchpoint sequence lies further upstream from the 3' splice site of intron 1 than is normally seen in plant introns. All dicotyledonous plant invertase genes contain this arrangement of sequence elements a distal branchpoint sequence and adjacent, downstream U-rich region. Intron 1 sequences upstream of the branchpoint and sequences in exons 1, 2, or 3 do not determine inclusion, suggesting that intron or exon splicing enhancer elements seen in vertebrate mini-exon systems are absent. In addition, mutation of the 3' and 5' splice sites flanking the mini-exon cause skipping of the mini-exon, suggesting that both splice sites are required. The branchpoint/U-rich sequence is able to promote splicing of mini-exons of 6, 3, and 1 nt in length and of a chicken cTNT mini-exon of 6 nt. These sequence elements therefore act as a splicing enhancer and appear to function via interactions between factors bound at the branchpoint/U-rich region and at the 5' splice site of intron 2, activating removal of this intron followed by removal of intron 1. This first example of splicing of a plant mini-exon to be analyzed demonstrates that particular arrangement of standard plant intron splicing signals can drive constitutive splicing of a mini-exon.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Solanum tuberosum
/
RNA Mensageiro
/
Éxons
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RNA de Plantas
/
Glicosídeo Hidrolases
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
RNA
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Reino Unido
País de publicação:
EEUU
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ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
/
UNITED STATES
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UNITED STATES OF AMERICA
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US
/
USA