Related Experiment Video

Updated: Jul 9, 2026

Overexpressing and Purifying a Toxic Nuclease from Escherichia coli
08:13

Overexpressing and Purifying a Toxic Nuclease from Escherichia coli

Published on: August 29, 2025

Calpain 1 and 2 are required for RNA replication of echovirus 1

Paula Upla1, Varpu Marjomäki, Liisa Nissinen

  • 1Department of Biochemistry and Food Chemistry, University of Turku, FI-20520 Turku, Finland.

Journal of Virology
|November 23, 2007
PubMed

Insights

Calpains are crucial for human echovirus 1 (EV1) replication. Inhibiting calpain 1 and calpain 2 blocks EV1 RNA synthesis and particle production, essential for viral infection.

Area of Science:

  • Virology
  • Molecular Biology
  • Biochemistry

Background:

  • Calpains are calcium-dependent cysteine proteases involved in protein degradation.
  • Human echovirus 1 (EV1) is a significant human pathogen.

Purpose of the Study:

  • To investigate the role of calpains in the life cycle of human echovirus 1 (EV1).
  • To determine if calpain inhibition affects EV1 infection and replication.

Main Methods:

  • Utilized calpain inhibitors (calpeptin, calpain inhibitor 1, calpain inhibitor 2) and short interfering RNAs (siRNAs) targeting calpain 1 and 2.
  • Employed confocal and immunoelectron microscopy to visualize viral components and calpains.
  • Assessed viral RNA synthesis and particle production following calpain inhibition.

Main Results:

  • Calpain inhibitors and siRNAs completely blocked EV1 infection.
  • Inhibition was observed for other picornaviruses, including human parechovirus 1 and coxsackievirus B3.
  • EV1 infection increased calpain activity, and calpains were found in EV1-associated vesicles.
  • Calpains are essential for viral RNA replication and production of new EV1 particles, but not for virus entry.

Conclusions:

  • Calpain 1 and calpain 2 are essential for the replication of EV1 RNA.
  • Calpains play a critical role in the later stages of EV1 infection, specifically in viral RNA synthesis and particle assembly.

More Related Videos

Analysis of Group IV Viral SSHHPS Using In Vitro and In Silico Methods10:40

Analysis of Group IV Viral SSHHPS Using In Vitro and In Silico Methods

Published on: December 21, 2019

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus09:08

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus

Published on: July 27, 2021

Related Concept Videos

Leaky Scanning02:28

Leaky Scanning

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 stands for...
DNA Helicases00:55

DNA Helicases

DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
Eukaryotic RNA Polymerases00:58

Eukaryotic RNA Polymerases

RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
Eukaryotic RNA Polymerases00:58

Eukaryotic RNA Polymerases

RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...
Transcription Initiation01:47

Transcription Initiation

Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...
The Replisome03:01

The Replisome

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...