Related Experiment Video
Updated: May 6, 2026
13:04
A Protocol for Analyzing Hepatitis C Virus Replication
Published on: June 26, 2014
23.7K
Functional and genetic analysis of coronavirus replicase-transcriptase proteins
Stanley G Sawicki1, Dorothea L Sawicki, Diane Younker
1Department of Medical Microbiology and Immunology, Medical University of Ohio, Toledo, Ohio, USA.
Plos Pathogens
|December 13, 2005
Summary
Researchers analyzed temperature-sensitive mutants of Murine hepatitis virus (MHV-A59) to understand viral RNA synthesis. This study identifies key proteins essential for the replicase-transcriptase complex and proposes a model for viral RNA production.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Coronaviruses utilize a replicase-transcriptase complex for RNA synthesis.
- Understanding this complex is crucial for developing antiviral strategies.
Purpose of the Study:
- To genetically and functionally analyze temperature-sensitive mutants of Murine hepatitis virus (MHV-A59).
- To identify essential viral proteins involved in RNA synthesis.
- To elucidate the pathway of viral RNA synthesis in MHV-A59-infected cells.
Main Methods:
- Genetic and functional analysis of 19 temperature-sensitive (ts) mutants of MHV-A59.
- Classical and biochemical complementation analysis.
- Identification of mutations in specific non-structural proteins (nsps).
- Analysis of viral RNA synthesis in ts mutant-infected cells.
Main Results:
- The majority of MHV-A59 ORF1a replicase proteins (nsp1-nsp11) form a single complementation group.
- Replicase proteins in ORF1b (nsp12-nsp16) function in trans and form at least three to five complementation groups.
- Mutations in nsp 4, 5, 10, 12, 14, and 16 were identified, confirming their essential role in the replicase-transcriptase complex.
- Three distinct RNA synthesis phenotypes were observed in mutants: defective negative-strand synthesis, failure to utilize negative strands for positive-strand synthesis, and defective elongation of both RNA strands.
Conclusions:
- Specific non-structural proteins are essential for a functional replicase-transcriptase complex.
- A model for viral RNA synthesis in MHV-A59-infected cells is proposed.
- Further biochemical analysis will refine the understanding of the RNA synthesis pathway and protein functions.
Related Concept Videos
03:01The Replisome
31.2K
DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with...
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with...
31.2K
02:28Leaky Scanning
4.5K
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R...
4.5K
01:26Size and Structure of Viral Genomes
1.2K
Viral genomes exhibit remarkable diversity in size, structure, and composition, influencing their replication strategies and interactions with host cells. These genomes consist of either DNA or RNA and may be linear or circular. Additionally, they can be single-stranded or double-stranded, with each configuration affecting how the virus propagates within a host. RNA viruses, for instance, generally have smaller genomes than DNA viruses, a factor that contributes to their high mutation rates and...
1.2K
01:29Viruses with RNA Genomes
1.5K
RNA viruses are categorized into positive-strand, negative-strand, or double-stranded groups based on their genomic structure and replication mechanisms. This classification dictates how they exploit host cellular machinery for protein synthesis and replication. Some RNA viruses also utilize reverse transcription as part of their life cycle, further diversifying their replication strategies.Positive-Strand RNA VirusesPositive-strand RNA viruses have genomes that function directly as messenger...
1.5K