Murine leukemia virus protease is encoded by the gag-pol gene and is synthesized through suppression of an amber termination codon.

Abstract

Murine leukemia virus protease is encoded by the gag-pol gene and is synthesized through suppression of an amber termination codon (retroviral ABSTRACTWe have purified from Moloney murine leukemia virus (Mo-MuLV) a protease that has the capacity of accurately cleaving the polyprotein precursor Pr65m into the mature viral structural proteins. Both the NH2-and COOHterminal amino acid sequences have been determined and aligned with the amino acid sequence deduced from the DNA sequence of Mo-MuLV by other workers. The results show that: (1) the protease is located at the 5' end of thepol gene, and the rst four amino acids are overlapped with the 3' end of the

Stop making sense or Regulation at the level of termination in eukaryotic protein synthesis

“…This tRNA which exists as a minor species in normal mouse cells, is markedly increased in MO-MuLV infected cells [3 11. This observation supports the hypothesis that GlntRNAumuo is actually involved in the readthrough occurring during MO-MuLV gene expression in vivo: indeed it was shown by protein analysis that a Gln residue is inserted in response to the UAG codon located at the end of the gag gene [32].…”

“…The region spanning the end of the gag gene and the beginning of thepol gene (encompassing the amber termination codon), encodes the viral protease responsible for cleavage of the gag polyprotein precursor into the mature core proteins [45]. The protease from MO-MuLV [32] has been sequenced establishing the suppression event and revealing the presence of a Gln inserted in response to the nonsense codon (see section 3.2).…”

“…In this regard, the case of FeLV is instructive. The nucleotide sequence of one strain (subgroup B) suggests a strategy of expression of the third class [62] whereas the partial sequence of the protease of another strain (strain AB) seems to indicate a first class type of gene expression [63]. This discrepancy may of course rely on the fact that the sequenced cDNA clone of FeLV (subgroup B) could correspond to a defective RNA [63].…”

“…The nucleotide sequence of one strain (subgroup B) suggests a strategy of expression of the third class [62] whereas the partial sequence of the protease of another strain (strain AB) seems to indicate a first class type of gene expression [63]. This discrepancy may of course rely on the fact that the sequenced cDNA clone of FeLV (subgroup B) could correspond to a defective RNA [63]. However, if one assumes that the nucleotide sequence of strain AB is identical to that of subgroup B, one should envisage the combination of a readthrough and a frameshift event to account for FeLV protease synthesis, and thus the creation of a fifth class of gene expression among retroviruses.…”

Mechanical Unfolding of the Beet Western Yellow Virus −1 Frameshift Signal

“…The Beet Western Yellow Virus (BWYV) belongs to the family of plant luteoviruses regulating the expression of its RNA-dependent RNA polymerase by programmed -1 frameshifting in a fashion identical to the well-known gag-pol retroviral frameshifting (38,45,54,55). Translational recoding by -1 frameshifting occurs in response to a specific downstream mRNA structure, usually a pseudoknot, which resists unwinding while the ribosome is paused over a "slippery sequence" (16,42).…”