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Molecular cloning and sequence analysis of the human parainfluenza 3 virus mRNA encoding the P and C proteins
Abstract:
The sequence of the mRNA encoding the phosphoprotein (P protein) of the human parainfluenza virus 3 (PF3) was determined by molecular cloning. In other Parmyxoviridae the P protein mRNA is functionally bicistronic and encodes an additional smaller nonstructural protein termed C. In this report three open reading frames (ORF) are described. These consist of a single long ORF encoding the P protein, and two shorter ORFs encoding the structural Vp18 protein (analogous to the Sendai C protein) and a putative polypeptide termed D protein. The encoded phosphoprotein consists of 603 amino acids and has a predicted molecular weight of 67,683. The C protein consists of 199 amino acids and has a predicted molecular weight of 23,288. The D protein consists of 140 amino acids and has a predicted molecular weight of 16,270. Although the D protein has not yet been demonstrated in vivo its synthesis could be demonstrated in vitro using a rabbit reticulocyte lysate system. Thus it appears that unlike the other paramyxoviruses, the PF3 P protein mRNA may be functionally tricistronic.
Insights
Human parainfluenza virus 3 (PF3) phosphoprotein mRNA sequencing revealed three open reading frames (ORFs). This suggests PF3 P protein mRNA may be functionally tricistronic, unlike other paramyxoviruses.
Area of Science:
- Virology
- Molecular Biology
- Genomics
Background:
- Human parainfluenza virus 3 (PF3) is a significant respiratory pathogen.
- Paramyxoviridae family viruses often exhibit complex gene expression strategies.
Purpose of the Study:
- To determine the mRNA sequence encoding the phosphoprotein (P protein) of human parainfluenza virus 3 (PF3).
- To investigate the potential for additional protein products from the PF3 P protein mRNA.
Main Methods:
- Molecular cloning techniques were employed to determine the mRNA sequence.
- In vitro synthesis of proteins was performed using a rabbit reticulocyte lysate system.
Main Results:
- Three distinct open reading frames (ORFs) were identified within the PF3 P protein mRNA.
- These ORFs encode the P protein, a Vp18 protein (analogous to Sendai C protein), and a putative D protein.
- The D protein's synthesis was demonstrated in vitro, suggesting its potential existence.
Conclusions:
- Unlike other paramyxoviruses where P protein mRNA is bicistronic, PF3 P protein mRNA appears to be functionally tricistronic.
- This finding expands our understanding of gene expression complexity within the Paramyxoviridae family.