Interaction of the FLP recombinase of the Saccharomyces cerevisiae 2 micron plasmid with mutated target sequences.

The 2 micron plasmid of Saccharomyces cerevisiae codes for a site-specific recombinase, the FLP protein, that catalyzes efficient recombination across two 599-base-pair (bp) inverted repeats of the plasmid DNA both in vivo and in vitro. We analyzed the interaction of the purified FLP protein with the target sequences of two point mutants that exhibit impaired FLP-mediated recombination in vivo. One mutation lies in one of the 13-bp repeat elements that had been previously shown to be protected from DNase digestion by the FLP protein. This mutation dramatically reduces FLP-mediated recombination in vitro and appears to act by reducing the binding of FLP protein to its target sequence. The second mutation lies within the 8-bp core region of the FLP target sequence. The FLP protein introduces staggered nicks surrounding this 8-bp region, and these nicks are thought to define the sites of strand exchange. The mutation in the core region abolishes recombination with a wild-type site. However, recombination between two mutated sites is very efficient. This result suggests that proper base pairing between the two recombining sites is an important feature of FLP-mediated recombination.

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The FLP recombinase of the Saccharomyces cerevisiae 2 microns plasmid attaches covalently to DNA via a phosphotyrosyl linkage.

Molecular and Cellular Biology ◽

10.1128/mcb.5.11.3274 ◽

1985 ◽

Vol 5 (11) ◽

pp. 3274-3279 ◽

Cited By ~ 52

Author(s):

R M Gronostajski ◽

P D Sadowski

Keyword(s):

Saccharomyces Cerevisiae ◽

Dna Sequences ◽

Flp Recombinase ◽

Specific Target ◽

Target Sites ◽

Dna Strands ◽

2 Micron Plasmid ◽

Dna Strand

The FLP recombinase, encoded by the 2 micron plasmid of Saccharomyces cerevisiae, promotes efficient recombination in vivo and in vitro between its specific target sites (FLP sites). It was previously determined that FLP interacts with DNA sequences within its target site (B. J. Andrews, G. A. Proteau, L. G. Beatty, and P. D. Sadowski. Cell 40:795-803, 1985), generates a single-stranded break on both DNA strands within the FLP site, and remains covalently attached to the 3' end of each break. We now show that the FLP protein is bound to the 3' side of each break by an O-phosphotyrosyl residue and that it appears that the same tyrosyl residue(s) is used to attach to either DNA strand within the FLP site.

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The FLP recombinase of the Saccharomyces cerevisiae 2 microns plasmid attaches covalently to DNA via a phosphotyrosyl linkage

Molecular and Cellular Biology ◽

10.1128/mcb.5.11.3274-3279.1985 ◽

1985 ◽

Vol 5 (11) ◽

pp. 3274-3279

Author(s):

R M Gronostajski ◽

P D Sadowski

Keyword(s):

Saccharomyces Cerevisiae ◽

Dna Sequences ◽

Flp Recombinase ◽

Specific Target ◽

Target Sites ◽

Dna Strands ◽

2 Micron Plasmid ◽

Dna Strand

The FLP recombinase, encoded by the 2 micron plasmid of Saccharomyces cerevisiae, promotes efficient recombination in vivo and in vitro between its specific target sites (FLP sites). It was previously determined that FLP interacts with DNA sequences within its target site (B. J. Andrews, G. A. Proteau, L. G. Beatty, and P. D. Sadowski. Cell 40:795-803, 1985), generates a single-stranded break on both DNA strands within the FLP site, and remains covalently attached to the 3' end of each break. We now show that the FLP protein is bound to the 3' side of each break by an O-phosphotyrosyl residue and that it appears that the same tyrosyl residue(s) is used to attach to either DNA strand within the FLP site.

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3'-end-forming signals of yeast mRNA.

Molecular and Cellular Biology ◽

10.1128/mcb.15.11.5983 ◽

1995 ◽

Vol 15 (11) ◽

pp. 5983-5990 ◽

Cited By ~ 58

Author(s):

Z Guo ◽

F Sherman

Keyword(s):

Saccharomyces Cerevisiae ◽

Cleavage Sites ◽

Yeast Saccharomyces Cerevisiae ◽

Higher Eukaryotes ◽

A Site

It was previously shown that three distinct but interdependent elements are required for 3' end formation of mRNA in the yeast Saccharomyces cerevisiae: (i) the efficiency element TATATA and related sequences, which function by enhancing the efficiency of positioning elements; (ii) positioning elements, such as TTAAGAAC and AAGAA, which position the poly(A) site; and (iii) the actual site of polyadenylation. In this study, we have shown that several A-rich sequences, including the vertebrate poly(A) signal AATAAA, are also positioning elements. Saturated mutagenesis revealed that optimum sequences of the positioning element were AATAAA and AAAAAA and that this element can tolerate various extents of replacements. However, the GATAAA sequence was completely ineffective. The major cleavage sites determined in vitro corresponded to the major poly(A) sites observed in vivo. Our findings support the assumption that some components of the basic polyadenylation machinery could have been conserved among yeasts, plants, and mammals, although 3' end formation in yeasts is clearly distinct from that of higher eukaryotes.

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High-throughput in vitro specificity profiling of natural and high-fidelity CRISPR-Cas9 variants

10.1101/2020.05.12.091991 ◽

2020 ◽

Author(s):

Karthik Murugan ◽

Arun S. Seetharam ◽

Andrew J. Severin ◽

Dipali G. Sashital

Keyword(s):

Genome Editing ◽

High Throughput ◽

Double Strand Breaks ◽

Target Sequence ◽

Wild Type ◽

Strand Breaks ◽

Cleavage Assay ◽

Target Sequences

AbstractCas9 is an RNA-guided endonuclease in the bacterial CRISPR-Cas immune system and a popular tool for genome editing. The most commonly used Cas9 variant, Streptococcus pyogenes Cas9 (SpCas9), is relatively non-specific and prone to off-target genome editing. Other Cas9 orthologs and engineered variants of SpCas9 have been reported to be more specific than wild-type (WT) SpCas9. However, systematic comparisons of the cleavage activities of these Cas9 variants have not been reported. In this study, we employed our high-throughput in vitro cleavage assay to compare cleavage activities and specificities of two natural Cas9 variants (SpCas9 and Staphylococcus aureus Cas9) and three engineered SpCas9 variants (SpCas9 HF1, HypaCas9, and HiFi Cas9). We observed that all Cas9s tested were able to cleave target sequences with up to five mismatches. However, the rate of cleavage of both on-target and off-target sequences varied based on the target sequence and Cas9 variant. For targets with multiple mismatches, SaCas9 and engineered SpCas9 variants are more prone to nicking, while WT SpCas9 creates double-strand breaks (DSB). These differences in cleavage rates and DSB formation may account for the varied specificities observed in genome editing studies. Our analysis reveals mismatch position-dependent, off-target nicking activity of Cas9 variants which have been underreported in previous in vivo studies.

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Saccharomyces cerevisiae SUP53 tRNA gene transcripts are processed by mammalian cell extracts in vitro but are not processed in vivo

Molecular and Cellular Biology ◽

10.1128/mcb.8.1.361-370.1988 ◽

1988 ◽

Vol 8 (1) ◽

pp. 361-370

Author(s):

S Ganguly ◽

P A Sharp ◽

U L RajBhandary

Keyword(s):

Saccharomyces Cerevisiae ◽

Mammalian Cells ◽

Wild Type ◽

Cell Extracts ◽

Amber Suppressor ◽

Gene Transcripts ◽

A Site ◽

Made In

We describe the results of our studies of expression of a Saccharomyces cerevisiae amber suppressor tRNA(Leu) gene (SUP53) in mammalian cells in vivo and in cell extracts in vitro. Parallel studies were carried out with the wild-type (Su-) tRNA(Leu) gene. Extracts from HeLa or CV1 cells transcribed both tRNA(Leu) genes. The transcripts were processed correctly at the 5' and 3' ends and accurately spliced to produce mature tRNA(Leu). Surprisingly, when the same tRNA(Leu) genes were introduced into CV1 cells, only pre-tRNAs(Leu) were produced. The pre-tRNAs(Leu) made in vivo were of the same size and contained the 5'-leader and 3'-trailer sequences as did pre-tRNAs(Leu) made in vitro. Furthermore, the pre-tRNAs(Leu) made in vivo were processed to mature tRNA(Leu) when incubated with HeLa cell extracts. A tRNA(Leu) gene from which the intervening sequence had been removed yielded RNAs that also were not processed at either their 5' or 3' termini. Thus, processing of pre-tRNA(Leu) in CV1 cells is blocked at the level of 5'- and 3'-end maturation. One possible explanation of the discrepancy in the results obtained in vivo and in vitro is that tRNA biosynthesis in mammalian cells involves transport of pre-tRNA from the site of its synthesis to a site or sites where processing takes place, and perhaps the yeast pre-tRNAs(Leu) synthesized in CV1 cells are not transported to the appropriate site.

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Saccharomyces cerevisiae SUP53 tRNA gene transcripts are processed by mammalian cell extracts in vitro but are not processed in vivo.

Molecular and Cellular Biology ◽

10.1128/mcb.8.1.361 ◽

1988 ◽

Vol 8 (1) ◽

pp. 361-370 ◽

Cited By ~ 2

Author(s):

S Ganguly ◽

P A Sharp ◽

U L RajBhandary

Keyword(s):

Saccharomyces Cerevisiae ◽

Mammalian Cells ◽

Wild Type ◽

Cell Extracts ◽

Amber Suppressor ◽

Gene Transcripts ◽

A Site ◽

Made In

We describe the results of our studies of expression of a Saccharomyces cerevisiae amber suppressor tRNA(Leu) gene (SUP53) in mammalian cells in vivo and in cell extracts in vitro. Parallel studies were carried out with the wild-type (Su-) tRNA(Leu) gene. Extracts from HeLa or CV1 cells transcribed both tRNA(Leu) genes. The transcripts were processed correctly at the 5' and 3' ends and accurately spliced to produce mature tRNA(Leu). Surprisingly, when the same tRNA(Leu) genes were introduced into CV1 cells, only pre-tRNAs(Leu) were produced. The pre-tRNAs(Leu) made in vivo were of the same size and contained the 5'-leader and 3'-trailer sequences as did pre-tRNAs(Leu) made in vitro. Furthermore, the pre-tRNAs(Leu) made in vivo were processed to mature tRNA(Leu) when incubated with HeLa cell extracts. A tRNA(Leu) gene from which the intervening sequence had been removed yielded RNAs that also were not processed at either their 5' or 3' termini. Thus, processing of pre-tRNA(Leu) in CV1 cells is blocked at the level of 5'- and 3'-end maturation. One possible explanation of the discrepancy in the results obtained in vivo and in vitro is that tRNA biosynthesis in mammalian cells involves transport of pre-tRNA from the site of its synthesis to a site or sites where processing takes place, and perhaps the yeast pre-tRNAs(Leu) synthesized in CV1 cells are not transported to the appropriate site.

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Effects of mutations in the Saccharomyces cerevisiae RNA14, RNA15, and PAP1 genes on polyadenylation in vivo.

Molecular and Cellular Biology ◽

10.1128/mcb.15.12.6979 ◽

1995 ◽

Vol 15 (12) ◽

pp. 6979-6986 ◽

Cited By ~ 35

Author(s):

E Mandart ◽

R Parker

Keyword(s):

Saccharomyces Cerevisiae ◽

Mrna Degradation ◽

Gene Products ◽

Polymerase Gene ◽

Cellular Processes ◽

Mutant Strains ◽

Cleavage And Polyadenylation ◽

A Site

The RNA14 and RNA15 gene products have been implicated in a variety of cellular processes. Mutations in these genes lead to faster decay of some mRNAs and yield extracts that are deficient in cleavage and polyadenylation in vitro. These results suggest that the RNA14 and RNA15 gene products may be involved in both adenylation and deadenylation in vivo. To explore the roles of these gene products in vivo, we examined the site of adenylation and the rate of deadenylation for individual mRNAs in rna14 and rna15 mutant strains. We observed that the rates of deadenylation are not affected by lesions in either the RNA14 or the RNA15 gene. This result suggests that the proteins encoded by these genes are not involved in regulation of the deadenylation rate. In contrast, we observed that the site of adenylation for the ACT1 transcript can be altered in these mutants. Interestingly, we also observed that mutation of the poly(A) polymerase gene altered the site of ACT1 polyadenylation. These observations suggest that the RNA14, RNA15, and PAP1 proteins are involved in poly(A) site choice. This alteration in poly(A) site choice in the rna14 mutant can be corrected by the ssm4 suppressor, indicating that this suppression acts at the level of polyadenylation and not by slowing mRNA degradation.

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