Presentation Title

Mutation Frequency of Escherichia coli strain Expressing a Quality Control Defective Phenylalanine-tRNA synthetase

Faculty Mentor

Beth Lazazzera

Start Date

23-11-2019 10:45 AM

End Date

23-11-2019 11:30 AM

Location

94

Session

poster 4

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Aminoacyl-tRNA synthetases (aaRSs) are enzymes that charge amino acids with their corresponding tRNA for translation. However, aaRSs can mis-aminoacylate tRNAs. When this occurs, aaRSs use their quality control (QC) function to recognize and correct the misacylated tRNAs. Previously, Escherichia coli cells lacking the QC function of isoleucyl-tRNA synthetase (IleRS) exhibited a higher mutation frequency in colonies under long-term incubation conditions. We seek to determine if the increased mutation frequency is specific to loss of QC by IleRS by assessing the mutation frequency of E. coli strain expressing an QC-defective phenylalanyl-tRNA synthetase (PheRS). To accomplish this, we have used a rifampicin-resistance assay and found that the QC-defective PheRS mutant showed a 9-fold higher frequency of rifampicin resistance mutants. To see if this increased mutation frequency is limited to rifampicin-resistance mutations, we will be using a Blue Papillation Assay, which assesses the frequency of reversion of the lacZ(E4461V) mutation. We used P1 transduction to create a mutant strain of E. coli containing a QC-defective PheRS allele and an F' episome carrying the lacZ(E461V) allele. These studies will determine whether a higher mutation frequency is a general property of cells that have lost QC by an aaRS enzyme.

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Nov 23rd, 10:45 AM Nov 23rd, 11:30 AM

Mutation Frequency of Escherichia coli strain Expressing a Quality Control Defective Phenylalanine-tRNA synthetase

94

Aminoacyl-tRNA synthetases (aaRSs) are enzymes that charge amino acids with their corresponding tRNA for translation. However, aaRSs can mis-aminoacylate tRNAs. When this occurs, aaRSs use their quality control (QC) function to recognize and correct the misacylated tRNAs. Previously, Escherichia coli cells lacking the QC function of isoleucyl-tRNA synthetase (IleRS) exhibited a higher mutation frequency in colonies under long-term incubation conditions. We seek to determine if the increased mutation frequency is specific to loss of QC by IleRS by assessing the mutation frequency of E. coli strain expressing an QC-defective phenylalanyl-tRNA synthetase (PheRS). To accomplish this, we have used a rifampicin-resistance assay and found that the QC-defective PheRS mutant showed a 9-fold higher frequency of rifampicin resistance mutants. To see if this increased mutation frequency is limited to rifampicin-resistance mutations, we will be using a Blue Papillation Assay, which assesses the frequency of reversion of the lacZ(E4461V) mutation. We used P1 transduction to create a mutant strain of E. coli containing a QC-defective PheRS allele and an F' episome carrying the lacZ(E461V) allele. These studies will determine whether a higher mutation frequency is a general property of cells that have lost QC by an aaRS enzyme.