Disease relevance of selA

• The nucleotide sequence of the selA gene from Escherichia coli whose product is involved in the conversion of seryl-tRNA(Sec UCA) into selenocysteyl-tRNA(Sec UCA) was determined. selA codes for a polypeptide of a calculated Mr of 50,667; a protein of appropriate size was synthesized in vivo in a T7 promoter/polymerase system [1].
• Selenophosphate as a substrate for mammalian selenocysteine synthase, its stability and toxicity [2].

High impact information on selA

• Efficient formation of selenocysteinyl-tRNA(Ser)(UCA) was achieved by using extracts in which both the selD and the selA gene products were overproduced [3].
• Both mutant tRNA variants, when charged with L-serine, were able to interact with selenocysteine synthase to give rise to selenocysteyl-tRNA with tRNA(Sec)(ExS) being as efficient as wild-type tRNA(Sec) [4].
• The product of the selA gene, selenocysteine synthase, is a pyridoxal 5-phosphate-containing enzyme which catalyzes the conversion of seryl-tRNA(Sec UCA) into selenocysteyl-tRNA(Sec UCA) [5].
• The N-terminal amino acid sequence of the purified protein was determined, and it confirmed that the initiation codon of selB mRNA translation overlaps the stop codon of the preceding selA gene by 4 bases [6].
• On the basis of sequence similarity, a conserved open reading frame has been annotated as a selenocysteine synthase gene in archaeal genomes [7].

Chemical compound and disease context of selA

• Selenocysteine synthase from Escherichia coli is a pyridoxal-5'-phosphate-containing enzyme which catalyses the conversion of seryl-tRNA(Sec) into selenocysteyl-tRNA(Sec) [8].
• In contrast, both archaeal and bacterial seryl-tRNA synthetases were able to charge both archaeal and bacterial tRNA(Sec) with serine, and E. coli selenocysteine synthase converted both types of seryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec) [7].

Biological context of selA

• In contrast, the other three sel genes (selA, -B, and -D) were shown to be constituents of two unlinked operons [9].
• By using Northern (RNA) gel blot analysis, the transcription start site was located within a 1.6-kilobase BglII-NcoI fragment 4.3 kilobases upstream from the fdhA gene [10].
• Se is an essential trace element and is found as a selenocysteine in the active site of Se-enzymes, such as glutathione peroxidase. tRNASec is first aminoacylated with serine by Ser RS and further is converted to selenocysteyl-tRNA by selenocysteine synthase [11].

Associations of selA with chemical compounds

• Analysis of amino acid sequences indicated that selenocysteine synthase belongs to the alpha/gamma superfamily of pyridoxal-5'-phosphate-dependent enzymes [8].
• These data together with the finding that selenophosphate synthetase is highly specific for selenide indicate that the phosphate moiety of selenophosphate provides selenocysteine synthase with the discrimination specificity against sulfur [8].
• It was found to be dependent on the positive control exerted by the fdhA, B and C genes, possibly involved in selenium incorporation, and by an hydB gene affecting the formate hydrogenlyase pathway [12].
• The apparent molecular mass of the native enzyme was determined by gel filtration to be about 100 kDa, which was confirmed by the fdhA nucleotide sequence. fdhA encodes for a pre-protein that differs from the truncated mature protein by an N-terminal 35-amino-acid signal peptide containing a twin arginine motif [13].
• The soluble periplasmic subunit of the formate dehydrogenase FdhA of the tetrachloroethene-reducing anaerobe Sulfurospirillum multivorans was purified to apparent homogeneity and the gene ( fdhA) was identified and sequenced [13].

Other interactions of selA

• Guided by principal component analysis, we instead discovered that the most efficient bacterial selenoprotein production conditions were obtained with the high-transcription T7lac-driven pET vector system in presence of the selA, selB, and selC genes, with induction of production at late exponential phase [14].

References