FTIR Spectroscopic Studies of Oligonucleotides That Model a Triple-Helical Domain in Self-Splicing Group I Introns†

Biochemistry ◽  
1997 ◽  
Vol 36 (49) ◽  
pp. 15463-15471 ◽  
Author(s):  
Munna Sarkar ◽  
Utz Dornberger ◽  
Eriks Rozners ◽  
Hartmut Fritzsche ◽  
Roger Strömberg ◽  
...  
Keyword(s):  
Spectroscopic Studies ◽  
Group I Introns ◽  
Helical Domain ◽  
Group I ◽  
Triple Helical Domain ◽  
Self Splicing

scholarly journals Mobile Self-Splicing Group I Introns from thepsbA Gene of Chlamydomonas reinhardtii: Highly Efficient Homing of an Exogenous Intron Containing Its Own Promoter

2001 ◽  
Vol 21 (10) ◽  
pp. 3472-3481 ◽  
Author(s):  
Obed W. Odom ◽  
Stephen P. Holloway ◽  
Nita N. Deshpande ◽  
Jaesung Lee ◽  
David L. Herrin
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Open Reading Frames ◽  
Group I Introns ◽  
Resistance Marker ◽  
Free Standing ◽  
Spectinomycin Resistance ◽  
Highly Efficient ◽  
Group I ◽  
Short Exon ◽  
Self Splicing

ABSTRACT Introns 2 and 4 of the psbA gene of Chlamydomonas reinhardtii chloroplasts (Cr.psbA2 andCr.psbA4, respectively) contain large free-standing open reading frames (ORFs). We used transformation of an intronless-psbA strain (IL) to test whether these introns undergo homing. Each intron, plus short exon sequences, was cloned into a chloroplast expression vector in both orientations and then cotransformed into IL along with a spectinomycin resistance marker (16Srrn). For Cr.psbA2, the sense construct gave nearly 100% cointegration of the intron whereas the antisense construct gave 0%, consistent with homing. For Cr.psbA4, however, both orientations produced highly efficient cointegration of the intron. Efficient cointegration of Cr.psbA4 also occurred when the intron was introduced as a restriction fragment lacking any known promoter. Deletion of most of the ORF, however, abolished cointegration of the intron, consistent with homing. TheCr.psbA4 constructs also contained a 3-(3,4-dichlorophenyl)-1,1-dimethylurea resistance marker in exon 5, which was always present when the intron integrated, thus demonstrating exon coconversion. Remarkably, primary selection for this marker gave >100-fold more transformants (>10,000/μg of DNA) than did the spectinomycin resistance marker. A trans homing assay was developed for Cr.psbA4; the ORF-minus intron integrated when the ORF was cotransformed on a separate plasmid. This assay was used to identify an intronic region between bp −88 and −194 (relative to the ORF) that stimulated homing and contained a possible bacterial (−10, −35)-type promoter. Primer extension analysis detected a transcript that could originate from this promoter. Thus, this mobile, self-splicing intron also contains its own promoter for ORF expression. The implications of these results for horizontal intron transfer and organelle transformation are discussed.

scholarly journals A Unique Group I Intron in Coxiella burnetii Is a Natural Splice Mutant

2009 ◽  
Vol 191 (12) ◽  
pp. 4044-4046 ◽  
Author(s):  
Rahul Raghavan ◽  
Linda D. Hicks ◽  
Michael F. Minnick
Keyword(s):  
Coxiella Burnetii ◽  
Group I Intron ◽  
23S Rrna ◽  
Rrna Gene ◽  
Group I Introns ◽  
Group I ◽  
23S Rrna Gene ◽  
Self Splicing

ABSTRACT Cbu.L1917, a group I intron present in the 23S rRNA gene of Coxiella burnetii, possesses a unique 3′-terminal adenine in place of a conserved guanine. Here, we show that, unlike all other group I introns, Cbu.L1917 utilizes a different cofactor for each splicing step and has a decreased self-splicing rate in vitro.

Bacterial origin of a chloroplast intron: conserved self-splicing group I introns in cyanobacteria

Science ◽  
1990 ◽  
Vol 250 (4987) ◽  
pp. 1566-1570 ◽  
Author(s):  
M. Xu ◽  
S. Kathe ◽  
H. Goodrich-Blair ◽  
S. Nierzwicki-Bauer ◽  
D. Shub
Keyword(s):  
Group I Introns ◽  
Bacterial Origin ◽  
Group I ◽  
Self Splicing

scholarly journals A Self-Splicing Group I Intron in DNA Polymerase Genes of T7-Like Bacteriophages

2004 ◽  
Vol 186 (23) ◽  
pp. 8153-8155 ◽  
Author(s):  
Richard P. Bonocora ◽  
David A. Shub
Keyword(s):  
Dna Polymerase ◽  
Group I Intron ◽  
Group I Introns ◽  
Homing Endonucleases ◽  
Structural Element ◽  
Group I ◽  
Close Relatives ◽  
Self Splicing

ABSTRACT Group I introns are inserted into genes of a wide variety of bacteriophages of gram-positive bacteria. However, among the phages of enteric and other gram-negative proteobacteria, introns have been encountered only in phage T4 and several of its close relatives. Here we report the insertion of a self-splicing group I intron in the coding sequence of the DNA polymerase genes of ΦI and W31, phages that are closely related to T7. The introns belong to subgroup IA2 and both contain an open reading frame, inserted into structural element P6a, encoding a protein belonging to the HNH family of homing endonucleases. The introns splice efficiently in vivo and self-splice in vitro under mild conditions of ionic strength and temperature. We conclude that there is no barrier for maintenance of group I introns in phages of proteobacteria.

Base pairing between the 3' exon and an internal guide sequence increases 3' splice site specificity in the Tetrahymena self-splicing rRNA intron

1990 ◽  
Vol 10 (6) ◽  
pp. 2960-2965
Author(s):  
E R Suh ◽  
R B Waring
Keyword(s):  
Splice Site ◽  
Site Specificity ◽  
Group I Introns ◽  
Base Pairing ◽  
Group I ◽  
Guide Sequence ◽  
Compensatory Mutations ◽  
Self Splicing ◽  
Splice Site Usage ◽  
Selection Of

It has been proposed that recognition of the 3' splice site in many group I introns involves base pairing between the start of the 3' exon and a region of the intron known as the internal guide sequence (R. W. Davies, R. B. Waring, J. Ray, T. A. Brown, and C. Scazzocchio, Nature [London] 300:719-724, 1982). We have examined this hypothesis, using the self-splicing rRNA intron from Tetrahymena thermophila. Mutations in the 3' exon that weaken this proposed pairing increased use of a downstream cryptic 3' splice site. Compensatory mutations in the guide sequence that restore this pairing resulted in even stronger selection of the normal 3' splice site. These changes in 3' splice site usage were more pronounced in the background of a mutation (414A) which resulted in an adenine instead of a guanine being the last base of the intron. These results show that the proposed pairing (P10) plays an important role in ensuring that cryptic 3' splice sites are selected against. Surprisingly, the 414A mutation alone did not result in activation of the cryptic 3' splice site.

Miniribozymes, small derivatives of the sunY intron, are catalytically active

1989 ◽  
Vol 9 (12) ◽  
pp. 5480-5483
Author(s):  
J A Doudna ◽  
J W Szostak
Keyword(s):  
Bacteriophage T4 ◽  
Complete Loss ◽  
The Self ◽  
Group I Introns ◽  
Structural Requirements ◽  
Group I ◽  
Catalytically Active ◽  
Conserved Core ◽  
Self Splicing ◽  
Derivatives Of

The self-splicing sunY intron from bacteriophage T4 has the smallest conserved core secondary structure of any of the active group I introns. Here we show that several nonconserved regions can be deleted from this intron without complete loss of catalytic activity. The 3' stems P9, P9.1, and P9.2 can be deleted while retaining 5' cleaving activity. Two base-paired stems (P7.1 and P7.2) that are peculiar to the group IA introns can also be deleted; however, the activities of the resulting derivatives depend greatly on the choice of replacement sequences and their lengths. The smallest active derivative is less than 180 nucleotides long. These experiments help to define the minimum structural requirements for catalysis.

scholarly journals Evaluating Group I Intron Catalytic Efficiency in Mammalian Cells

1999 ◽  
Vol 19 (10) ◽  
pp. 6479-6487 ◽  
Author(s):  
Meredith B. Long ◽  
Bruce A. Sullenger
Keyword(s):  
Rna Polymerase Ii ◽  
Mammalian Cells ◽  
Catalytic Efficiency ◽  
Human Cells ◽  
The Self ◽  
Group I Introns ◽  
Cellular Environment ◽  
Group I ◽  
Self Splicing ◽  
The Impact

ABSTRACT Recent reports have demonstrated that the group I ribozyme fromTetrahymena thermophila can performtrans-splicing reactions to repair mutant RNAs. For therapeutic use, such ribozymes must function efficiently when transcribed from genes delivered to human cells, yet it is unclear how group I splicing reactions are influenced by intracellular expression of the ribozyme. Here we evaluate the self-splicing efficiency of group I introns from transcripts expressed by RNA polymerase II in human cells to directly measure ribozyme catalysis in a therapeutically relevant setting. Intron-containing expression cassettes were transfected into a human cell line, and RNA transcripts were analyzed for intron removal. The percentage of transcripts that underwent self-splicing ranged from 0 to 50%, depending on the construct being tested. Thus, self-splicing activity is supported in the mammalian cellular environment. However, we find that the extent of self-splicing is greatly influenced by sequences flanking the intron and presumably reflects differences in the intron’s ability to fold into an active conformation inside the cell. In support of this hypothesis, we show that the ability of the intron to fold and self-splice from cellular transcripts in vitro correlates well with the catalytic efficiency observed from the same transcripts expressed inside cells. These results underscore the importance of evaluating the impact of sequence context on the activity of therapeutic group I ribozymes. The self-splicing system that we describe should facilitate these efforts as well as aid in efforts at enhancing in vivo ribozyme activity for various applications of RNA repair.

scholarly journals Base pairing between the 3' exon and an internal guide sequence increases 3' splice site specificity in the Tetrahymena self-splicing rRNA intron.

1990 ◽  
Vol 10 (6) ◽  
pp. 2960-2965 ◽  
Author(s):  
E R Suh ◽  
R B Waring
Keyword(s):  
Splice Site ◽  
Site Specificity ◽  
Group I Introns ◽  
Base Pairing ◽  
Group I ◽  
Guide Sequence ◽  
Compensatory Mutations ◽  
Self Splicing ◽  
Splice Site Usage ◽  
Selection Of

It has been proposed that recognition of the 3' splice site in many group I introns involves base pairing between the start of the 3' exon and a region of the intron known as the internal guide sequence (R. W. Davies, R. B. Waring, J. Ray, T. A. Brown, and C. Scazzocchio, Nature [London] 300:719-724, 1982). We have examined this hypothesis, using the self-splicing rRNA intron from Tetrahymena thermophila. Mutations in the 3' exon that weaken this proposed pairing increased use of a downstream cryptic 3' splice site. Compensatory mutations in the guide sequence that restore this pairing resulted in even stronger selection of the normal 3' splice site. These changes in 3' splice site usage were more pronounced in the background of a mutation (414A) which resulted in an adenine instead of a guanine being the last base of the intron. These results show that the proposed pairing (P10) plays an important role in ensuring that cryptic 3' splice sites are selected against. Surprisingly, the 414A mutation alone did not result in activation of the cryptic 3' splice site.

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