Proteolytic cleavage

Definition

Proteolytic cleavage is the biochemical process in which specific peptide bonds in a protein are hydrolyzed by proteolytic enzymes, resulting in the formation of smaller polypeptides or amino acids. This process is crucial in the maturation of viral proteins, as it often activates them or facilitates their proper assembly into functional virions. It plays a significant role in ensuring that viral components are correctly processed and can efficiently participate in the formation of new virus particles.

5 Must Know Facts For Your Next Test

1. Proteolytic cleavage is essential for the activation of certain viral proteins, enabling them to perform their specific functions during infection.
2. This process can occur at multiple stages during virion assembly and maturation, often leading to structural rearrangements necessary for viral stability.
3. Some viruses encode their own proteases to carry out this cleavage, while others rely on host cell proteases for processing their proteins.
4. Proteolytic cleavage can influence the pathogenicity of viruses, as improperly cleaved proteins may lead to non-infectious or less virulent forms.
5. The timing and regulation of proteolytic cleavage are critical for the synchronized assembly of viral components and their release from infected cells.

Review Questions

• How does proteolytic cleavage contribute to the activation of viral proteins during virion assembly?
  • Proteolytic cleavage plays a key role in activating viral proteins by selectively hydrolyzing specific peptide bonds. This process transforms precursor proteins into their functional forms, allowing them to participate in virion assembly. Without this precise cleavage, certain proteins may remain inactive or misfolded, which can disrupt the formation of infectious viral particles.
• Discuss the implications of using host cell proteases versus viral-encoded proteases for proteolytic cleavage in viruses.
  • The use of host cell proteases for proteolytic cleavage means that viruses must adapt to the host's cellular environment, potentially leading to variations in efficiency based on host factors. Conversely, when viruses encode their own proteases, they gain more control over the timing and specificity of cleavage events. This can enhance their ability to replicate and assemble efficiently, but may also make them more vulnerable to antiviral therapies targeting these viral proteases.
• Evaluate the potential consequences of dysregulated proteolytic cleavage on viral pathogenicity and virulence.
  • Dysregulated proteolytic cleavage can lead to significant changes in viral pathogenicity and virulence. If proteins are not cleaved at the correct sites or times, it can result in the production of non-infectious viral particles or attenuated strains that are less capable of causing disease. This misregulation can affect how effectively a virus spreads within a host or its ability to evade the immune response, ultimately impacting its overall survival and success as a pathogen.

Related terms

Protease: An enzyme that catalyzes the breakdown of proteins by hydrolyzing peptide bonds.

Virion: A complete virus particle that consists of genetic material surrounded by a protein coat, often with additional structures such as an envelope.

Post-translational modification: The chemical modification of a protein after its translation, which can include processes like phosphorylation, glycosylation, and cleavage.