scholarly journals One RNA plays three roles to provide catalytic activity to a group I intron lacking an endogenous internal guide sequence

2009 ◽  
Vol 37 (12) ◽  
pp. 3981-3989 ◽  
Author(s):  
Nilesh Vaidya ◽  
Niles Lehman
Keyword(s):  
Catalytic Activity ◽  
Group I Intron ◽  
Group I ◽  
Guide Sequence

scholarly journals Group I Intron Internal Guide Sequence Binding Strength as a Component of Ribozyme Network Formation

Molecules ◽  
2016 ◽  
Vol 21 (10) ◽  
pp. 1293 ◽  
Author(s):  
Laura Satterwhite ◽  
Jessica Yeates ◽  
Niles Lehman
Keyword(s):  
Network Formation ◽  
Group I Intron ◽  
Binding Strength ◽  
Group I ◽  
Guide Sequence

scholarly journals The conserved U.G pair in the 5' splice site duplex of a group I intron is required in the first but not the second step of self-splicing.

1989 ◽  
Vol 9 (9) ◽  
pp. 3657-3666 ◽  
Author(s):  
E T Barfod ◽  
T R Cech
Keyword(s):  
Splice Site ◽  
Group I Intron ◽  
Splice Site Mutation ◽  
Second Step ◽  
Site Mutation ◽  
Catalytic Rate Constant ◽  
Group I ◽  
Normal Site ◽  
Guide Sequence ◽  
Self Splicing

Group I self-splicing introns have a 5' splice site duplex (P1) that contains a single conserved base pair (U.G). The U is the last nucleotide of the 5' exon, and the G is part of the internal guide sequence within the intron. Using site-specific mutagenesis and analysis of the rate and accuracy of splicing of the Tetrahymena thermophila group I intron, we found that both the U and the G of the U.G pair are important for the first step of self-splicing (attack of GTP at the 5' splice site). Mutation of the U to a purine activated cryptic 5' splice sites in which a U.G pair was restored; this result emphasizes the preference for a U.G at the splice site. Nevertheless, some splicing persisted at the normal site after introduction of a purine, suggesting that position within the P1 helix is another determinant of 5' splice site choice. When the U was changed to a C, the accuracy of splicing was not affected, but the Km for GTP was increased by a factor of 15 and the catalytic rate constant was decreased by a factor of 7. Substitution of U.A, U.U, G.G, or A.G for the conserved U.G decreased the rate of splicing by an even greater amount. In contrast, mutation of the conserved G enhanced the second step of splicing, as evidenced by a trans-splicing assay. Furthermore, a free 5' exon ending in A or C instead of the conserved U underwent efficient ligation. Thus, unlike the remainder of the P1 helix, which functions in both the first and second steps of self-splicing, the conserved U.G appears to be important only for the first step.

The conserved U.G pair in the 5' splice site duplex of a group I intron is required in the first but not the second step of self-splicing

1989 ◽  
Vol 9 (9) ◽  
pp. 3657-3666
Author(s):  
E T Barfod ◽  
T R Cech
Keyword(s):  
Splice Site ◽  
Group I Intron ◽  
Splice Site Mutation ◽  
Second Step ◽  
Site Mutation ◽  
Catalytic Rate Constant ◽  
Group I ◽  
Normal Site ◽  
Guide Sequence ◽  
Self Splicing

Group I self-splicing introns have a 5' splice site duplex (P1) that contains a single conserved base pair (U.G). The U is the last nucleotide of the 5' exon, and the G is part of the internal guide sequence within the intron. Using site-specific mutagenesis and analysis of the rate and accuracy of splicing of the Tetrahymena thermophila group I intron, we found that both the U and the G of the U.G pair are important for the first step of self-splicing (attack of GTP at the 5' splice site). Mutation of the U to a purine activated cryptic 5' splice sites in which a U.G pair was restored; this result emphasizes the preference for a U.G at the splice site. Nevertheless, some splicing persisted at the normal site after introduction of a purine, suggesting that position within the P1 helix is another determinant of 5' splice site choice. When the U was changed to a C, the accuracy of splicing was not affected, but the Km for GTP was increased by a factor of 15 and the catalytic rate constant was decreased by a factor of 7. Substitution of U.A, U.U, G.G, or A.G for the conserved U.G decreased the rate of splicing by an even greater amount. In contrast, mutation of the conserved G enhanced the second step of splicing, as evidenced by a trans-splicing assay. Furthermore, a free 5' exon ending in A or C instead of the conserved U underwent efficient ligation. Thus, unlike the remainder of the P1 helix, which functions in both the first and second steps of self-splicing, the conserved U.G appears to be important only for the first step.

scholarly journals Lead cleavage sites in the core structure of group I intron-RNA

1993 ◽  
Vol 21 (2) ◽  
pp. 311-317 ◽  
Author(s):  
Barbara Striecjer ◽  
Uwe von Ahsen ◽  
Renée Schroeder
Keyword(s):  
Group I Intron ◽  
Core Structure ◽  
Cleavage Sites ◽  
The Core ◽  
Group I
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