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Messenger RNA encoding the phosphoprotein (P) gene of human parainfluenza virus 3 is bicistronic
Abstract:
The complete nucleotide sequence of the phosphoprotein (P) mRNA of human parainfluenza virus 3 (PIV-3) was derived from two cDNA clones spanning almost the entire P gene. The mRNA, excluding the poly(A) tail, is 2014 nucleotides long and is bicistronic. The first open reading frame (ORF) codes for the phosphoprotein (P) of mol wt 68,860. Seven nucleotides downstream from the first AUG codon, in a +1 reading frame, there is an additional ORF which can code for a polypeptide of mol wt 23,266. The latter protein appears to be similar to the C proteins found in cells infected with several paramyxoviruses. Comparison of the predicted amino acid sequence of the P and C proteins of PIV-3 with the corresponding Sendai virus proteins reveals considerable homology at the C-terminal half. In contrast, the P and C proteins of PIV-3 share very little homology with the measles virus P and C proteins, respectively.
Insights
Researchers sequenced the phosphoprotein (P) mRNA of human parainfluenza virus 3 (PIV-3), revealing a bicistronic structure encoding both P and a C protein. This PIV-3 C protein shows homology to Sendai virus but not measles virus proteins.
Area of Science:
- Virology
- Molecular Biology
- Genomics
Background:
- Human parainfluenza virus 3 (PIV-3) is a significant respiratory pathogen.
- Understanding viral gene expression is crucial for developing antiviral strategies.
Purpose of the Study:
- To determine the complete nucleotide sequence of the PIV-3 phosphoprotein (P) mRNA.
- To identify and characterize potential open reading frames (ORFs) within the P mRNA.
Main Methods:
- cDNA cloning and sequencing of PIV-3 mRNA.
- Bioinformatic analysis to identify ORFs and predict protein products.
- Comparative sequence analysis with related paramyxoviruses.
Main Results:
- The PIV-3 P mRNA is 2014 nucleotides long and bicistronic.
- It encodes a phosphoprotein (P) and a C protein, with the C protein ORF located in a +1 reading frame.
- The P and C proteins of PIV-3 exhibit significant C-terminal homology with Sendai virus proteins.
- Limited homology was observed between PIV-3 and measles virus P and C proteins.
Conclusions:
- The PIV-3 genome encodes at least two proteins from the P mRNA: P and C.
- The C protein of PIV-3 shares evolutionary links with other paramyxoviruses, particularly Sendai virus.
- Sequence divergence suggests distinct evolutionary paths between PIV-3 and measles virus.