Suppressor tRNA (suppressor + trna)

Distribution by Scientific Domains

Selected Abstracts

Evolution of Amber Suppressor tRNAs for Efficient Bacterial Production of Proteins Containing Nonnatural Amino Acids,

Jiantao Guo
Angewandte Evolution: Bereiche der M.-jannaschii -Tyrosyl-tRNACUA, von denen man annimmt, dass sie mit dem Elongationsfaktor Tu wechselwirken, wurden randomisiert und die erhaltenen tRNA-Bibliotheken der In-vitro-Evolution unterworfen. Die dabei identifizierten tRNAs lieferten Proteine mit nichtnatürlichen Aminosäuren in deutlich höheren Ausbeuten. Manchmal hing das Ausmaß der Verbesserung von der Aminosäure ab. [source]

SsrA-mediated protein tagging in the presence of miscoding drugs and its physiological role in Escherichia coli

GENES TO CELLS, Issue 7 2002
Tatsuhiko Abo
Background: We have shown recently that read-through of a normal stop codon by a suppressor tRNA in specific genes possessing a Rho-independent terminator leads to SsrA-mediated tagging of extended proteins in Escherichia coli cells. Miscoding antibiotics such as kanamycin and streptomycin reduce translational fidelity by binding to the 30S ribosomal subunit. The aim of the present study was to address how miscoding antibiotics affect the read-through of stop codons and SsrA-mediated protein tagging. Results: Miscoding antibiotics caused translational read-through of stop codons when added to the culture medium at sublethal concentrations. Under the same conditions, the drugs enhanced SsrA-mediated tagging of bulk cellular proteins, as observed in cells carrying an ochre suppressor tRNA. Translational read-through products generated from the crp gene in the presence of the antibiotics was efficiently tagged by the SsrA system, presumably because the ribosome reached the 3, end of the mRNA defined by the terminator hairpin. The SsrA-defective cells were more sensitive to the miscoding antibiotics compared to the wild-type cells. Conclusion: We conclude that the SsrA system contributes to the survival of cells by dealing with translational errors in the presence of low concentrations of miscoding antibiotics. [source]

Site-specific incorporation of unnatural amino acids into urate oxidase in Escherichia coli

PROTEIN SCIENCE, Issue 10 2008
Mingjie Chen
Abstract Urate oxidase catalyzes the oxidation of uric acid with poor solubility to produce 5-hydroxyisourate and allantoin. Since allantoin is excreted in vivo, urate oxidase has the potential to be a therapeutic target for the treatment of gout. However, its severe immunogenicity limits its clinical application. Furthermore, studies on the structure,function relationships of urate oxidase have proven difficult. We developed a method for genetically incorporating p -azido-L-phenylalanine into target protein in Escherichia coli in a site-specific manner utilizing a tyrosyl suppressor tRNA/aminoacyl-tRNA synthetase system. We substituted p -azido-L-phenylalanine for Phe170 or Phe281 in urate oxidase. The products were purified and their enzyme activities were analyzed. In addition, we optimized the system by adding a "Shine-Dalgarno (SD) sequence" and tandem suppressor tRNA. This method has the benefit of site-specifically modifying urate oxidase with homogeneous glycosyl and PEG derivates, which can provide new insights into structure,function relationships and improve pharmacological properties of urate oxidase. [source]