Possible incorporation of phosphoserine into globin readthrough protein via bovine opal suppressor phosphoseryl‐tRNA

Mizutani, Takaharu; Tachibana, Yoshio

doi:10.1016/0014-5793(86)80032-1

Cited by 25 publications

(8 citation statements)

References 25 publications

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“…For example, the poor rate of dephosphorylation of phosphoseryl-tRNA [Ser]Sec by PSTK observed in the present study suggests that the phosphate group cannot readily be removed, as has similarly been found for other kinases, unless the unlikely possibility of a specific phosphatase might exist. Furthermore, seryl-tRNA [Ser]Sec is an authentic suppressor tRNA that decodes UGA stop codons in vivo (28), and phosphoseryl-tRNA [Ser]Sec is capable of decoding UGA in vitro (29), suggesting that these forms of tRNA [Ser]Sec are likely maintained intracellularly only transiently as substrates for other reactions. Seryl-tRNA [Ser]Sec is a substrate for PSTK, and if the product of this reaction is not an intermediate in the biosynthesis of Sec, then seryl-tRNA [Ser]Sec would also be used in Sec biosynthesis by another route.…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of phosphoseryl-tRNA ^[Ser]Sec kinase

Carlson

Kryukov

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

174

187

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In 1970, a kinase activity that phosphorylated a minor species of seryl-tRNA to form phosphoseryl-tRNA was found in rooster liver [Maenpaa, P. H. & Bernfield, M. R. (1970) Proc. Natl. Acad. Sci. USA 67, 688 -695], and a minor seryl-tRNA that decoded the nonsense UGA was detected in bovine liver. The phosphoseryl-tRNA and the minor UGA-decoding seryl-tRNA were subsequently identified as selenocysteine (Sec) tRNA [Ser]Sec , but the kinase activity remained elusive. Herein, by using a comparative genomics approach that searched completely sequenced archaeal genomes for a kinase-like protein with a pattern of occurrence similar to that of components of Sec insertion machinery, we detected a candidate gene for mammalian phosphoseryl-tRNA [ S elenocysteine (Sec) has its own code word, UGA, and its own tRNA, and therefore is viewed as the 21st amino acid in the genetic code (reviewed in refs. 1-4). Although UGA usually codes for the termination of protein synthesis, it also specifies Sec if specific requirements are met. The presence of a stemloop structure downstream of UGA, called a Sec insertion sequence (SECIS) element, is the critical component in selenoprotein mRNAs that dictates UGA to code for Sec (reviewed in ref. 5). In mammals, the SECIS element occurs in the 3Ј untranslated region of selenoprotein mRNAs. A specific elongation factor, EFsec, specifically recognizes selenocysteyltRNA [Ser]Sec (6, 7), and a SECIS element binding protein, SBP2, binds specifically to the SECIS element (8), directing the insertion of Sec into protein in response to UGA.It has been known for several years that the biosynthesis of Sec occurs on its tRNA in both bacteria (9) and mammals (10) after the tRNA is initially aminoacylated with serine by seryl-tRNA synthetase. In Escherichia coli, the pathway for the biosynthesis of Sec has been completely established (reviewed in ref. 1). After the aminoacylation of bacterial tRNA [Ser]Sec with serine, the hydroxyl group is removed from the seryl moiety to yield an aminoacrylyl intermediate, and this step is catalyzed by a pyridoxal phosphate-dependent Sec synthase. The aminoacrylyl intermediate serves as the acceptor for the activated selenium donor, monoselenophosphate, which is synthesized from selenite and ATP in the presence of selenophosphate synthetase (reviewed in ref. 1). Once selenium is donated to the intermediate, the biosynthesis of Sec on tRNA [Ser]Sec is complete.In eukaryotes, however, the biosynthesis of Sec has not been established, but several components have been identified over the years that play a role in this process. For example, in 1970, a minor seryl-tRNA was reported to form phosphoseryl-tRNA by a kinase activity from rooster liver (11), and a minor seryl-tRNA from bovine, rabbit, and chicken livers was reported to specifically decode the nonsense codon UGA (12). Although it was subsequently shown that both the minor seryl-tRNA that formed phosphoseryl-tRNA and the one that decoded UGA were the same tRNA (13), it was not known at the time these components were ...

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Section: Discussionmentioning

confidence: 99%

Identification and characterization of phosphoseryl-tRNA ^[Ser]Sec kinase

Carlson

Kryukov

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

174

187

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“…Interestingly the tRNAsec is initially charged with L-serine by seryl-tRNA synthetase and is then converted to selenocysteyl-tRNAS'. An intermediate in the biosynthesis of the selenocysteyl-tRNAS' in mammalian cells appears to be a phosphoseryl-tRNAser and there is evidence from in vitro translation studies that phosphoserine can be incorporated into 13-globin in response to the natural UGA terminator (Mizutani and Tachibana, 1986). It is possible that the C.albicans tRNACAG is charged with serine which is then phosphorylated by a kinase present in a wide range of eukaryotic species.…”

Section: Discussionmentioning

confidence: 99%

Non-standard translational events in Candida albicans mediated by an unusual seryl-tRNA with a 5′-CAG-3′ (leucine) anticodon.

1993

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From in vitro translation studies we have previously demonstrated the existence of an apparent efficient UAG (amber) suppressor tRNA in the dimorphic fungus Candida albicans (Santos et al., 1990). Using an in vitro assay for termination codon readthrough the tRNA responsible was purified to homogeneity from C.albicans cells. The determined sequence of the purified tRNA predicts a 5′‐CAG‐3′ anticodon that should decode the leucine codon CUG and not the UAG termination codon as originally hypothesized. However, the tRNA(CAG) sequence shows greater nucleotide homology with seryl‐tRNAs from the closely related yeast Saccharomyces cerevisiae than with leucyl‐tRNAs from the same species. In vitro tRNA‐charging studies demonstrated that the purified tRNA(CAG) is charged with Ser. The gene encoding the tRNA was cloned from C.albicans by a PCR‐based strategy and DNA sequence analysis confirmed both the structure of the tRNA(CAG) and the absence of any introns in the tRNA gene. The copy number of the tRNA(CAG) gene (1–2 genes per haploid genome) is in agreement with the relatively low abundance (< 0.5% total tRNA) of this tRNA. In vitro translation studies revealed that the purified tRNA(CAG) could induce apparent translational bypass of all three termination codons. However, peptide mapping of in vitro translation products demonstrated that the tRNA(CAG) induces translational misreading in the amino‐terminal region of two RNA templates employed, namely the rabbit alpha‐ and beta‐globin mRNAs. These results suggest that the C.albicans tRNA(CAG) is not an ‘omnipotent’ suppressor tRNA but rather may mediate a novel non‐standard translational event in vitro during the translation of the CUG codon. The possible nature of this non‐standard translation event is discussed in the context of both the unusual structural features of the tRNA(CAG) and its in vitro behaviour.

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“…In the presence of seryl-tRNA(Ser)Sec or phosphoseryl-tRNA(ser)sec, the UGA codon of glutathione peroxidase mRNA is translated to yield a protein product that reacts with antibodies against glutathione peroxidase (Lee et al, 1989b). However, the direct incorporation of phosphoserine into protein via phosphoseryl-tRNA(ser)Sec remains to be demonstrated (Mizutani and Tachibana, 1986). Another possible role of phosphoseryl-tRNA concerns its function in the biosynthesis of serine (Maenpaa and Bernfield, 1970;Sharp and Stewart, 1977) or in the reverse metabolic pathway from serine to 3-phosphohydroxypyruvate .…”

Section: Discussionmentioning

confidence: 99%

“…Another possible role of phosphoseryl-tRNA concerns its function in the biosynthesis of serine (Maenpaa and Bernfield, 1970;Sharp and Stewart, 1977) or in the reverse metabolic pathway from serine to 3-phosphohydroxypyruvate . Thus far, in vitro studies of the function of phosphoseryl-tRNA(ser)se have been unsuccessful (Maenpaa and Bernfield, 1970;Mizutani and Tachibana, 1986;Mizutani, 1989). After the major identity element for serine phosphorylation has been identified, the biological function of phosphoseryl-tRNA(ser)sec should be elucidated.…”

Section: Discussionmentioning

confidence: 99%

The length and the secondary structure of the D-stem of human selenocysteine tRNA are the major identity determinants for serine phosphorylation.

Groß

1994

The EMBO Journal

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Selenocysteine tRNA [tRNA(Ser)Sec] has been shown to be serylated by tRNA(Ser) synthetase. The serine moiety of seryl‐tRNA(Ser)Sec in vertebrates is further phosphorylated by a kinase, in addition to being converted into selenocysteine. Using site‐directed mutagenesis we have introduced a number of mutations into T7 RNA polymerase transcripts of human tRNA(Ser)Sec. Our results show that most of the unique structural features of tRNA(Ser)(Sec), like the 5′‐triphosphate, the 9 bp long acceptor stem and the anticodon, are not identity elements for phosphorylation of human seryl‐tRNA(Ser)Sec. However, the length and secondary structure of the D‐stem (6 bp in contrast with 4 bp in the canonical serine tRNA) of human tRNA(Ser)Sec, but not its sequence, are the major identity determinants which discriminate this tRNA from common tRNA(Ser) and identify it as the substrate for phosphorylation by seryl‐tRNA(Ser)Sec kinase. This notion is confirmed by the fact that normal seryl‐tRNA(Ser), which is not a substrate for serine phosphorylation, becomes a substrate if two additional base pairs are introduced into its D‐stem.

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Possible incorporation of phosphoserine into globin readthrough protein via bovine opal suppressor phosphoseryl‐tRNA

Cited by 25 publications

References 25 publications

Identification and characterization of phosphoseryl-tRNA ^[Ser]Sec kinase

Identification and characterization of phosphoseryl-tRNA ^[Ser]Sec kinase

Non-standard translational events in Candida albicans mediated by an unusual seryl-tRNA with a 5′-CAG-3′ (leucine) anticodon.

The length and the secondary structure of the D-stem of human selenocysteine tRNA are the major identity determinants for serine phosphorylation.

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Possible incorporation of phosphoserine into globin readthrough protein via bovine opal suppressor phosphoseryl‐tRNA

Cited by 25 publications

References 25 publications

Identification and characterization of phosphoseryl-tRNA [Ser]Sec kinase

Identification and characterization of phosphoseryl-tRNA [Ser]Sec kinase

Non-standard translational events in Candida albicans mediated by an unusual seryl-tRNA with a 5′-CAG-3′ (leucine) anticodon.

The length and the secondary structure of the D-stem of human selenocysteine tRNA are the major identity determinants for serine phosphorylation.

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Identification and characterization of phosphoseryl-tRNA ^[Ser]Sec kinase

Identification and characterization of phosphoseryl-tRNA ^[Ser]Sec kinase