[Paper Review] Biology of Prions

Veronica Ines Cacace|arXiv (Cornell University)|Jun 17, 2011

Prion Diseases and Protein Misfolding88 references3 citations

TL;DR

This paper reviews the biology of prions, focusing on the mammalian PrP prion and fungal prions, proposing that prions—proteinaceous infectious particles—function as infectious agents without nucleic acids by transmitting genetic information through conformational changes in protein structure. The key contribution is the emerging view that prions may play essential biological roles in cellular function and evolutionary plasticity, challenging their sole association with disease.

ABSTRACT

In this paper we will review various aspects of the biology of prions and focus on what is currently known about the mammalian PrP prion. Also we briefly describe the prions of yeast and other fungi. Prions are infectious proteins behaving like genes, i.e. proteins that not only contain genetic information in its tertiary structure, i.e. its shape, but are also able to transmit and replicate in a manner analogous to genes but through very different mechanisms. The term prion is derived from proteinaceous infectious particle and arose from the Prusiner hypothesis that the infectious agent of certain neurodegenerative diseases was only in a protein, without the participation of nucleic acids. Currently there are several known types of prion, in addition to the originally described, which are pathogens of mammals, yeast and other fungi. Prion proteins are ubiquitous and not always detrimental to their hosts. This vision of the prion as a causative agent of disease is changing, finding more and more evidence that they could have important roles in cells and contribute to the phenotypic plasticity of organisms through the mechanisms of evolution.

Motivation & Objective

• To review current knowledge on mammalian PrP prion biology and its role in neurodegenerative diseases.
• To examine the structure and function of prions in yeast and other fungi.
• To challenge the traditional view of prions as solely pathogenic agents by exploring their potential physiological roles.
• To investigate how prion conformational changes can transmit information akin to genetic inheritance.
• To assess the implications of prions for phenotypic plasticity and evolutionary mechanisms.

Proposed method

• Analytical review of existing literature on prion structure, replication, and transmission mechanisms.
• Examination of the Prusiner hypothesis that prions are infectious agents composed solely of protein.
• Comparison of mammalian prions with fungal prions based on protein folding and propagation dynamics.
• Evaluation of experimental evidence linking prion conformations to heritable phenotypic traits.
• Integration of findings on prion function in cellular processes and evolution.

Experimental results

Research questions

• RQ1 How do prions transmit infectious information without nucleic acids?
• RQ2 What is the role of protein conformation in prion replication and propagation?
• RQ3 In what ways do prions contribute to phenotypic plasticity in organisms?
• RQ4 How do fungal prions compare to mammalian prions in structure and function?
• RQ5 What evidence supports the idea that prions are not only pathogenic but also biologically functional?

Key findings

• Prions are infectious proteins that transmit biological information through their tertiary structure, specifically their conformational shape.
• The mammalian PrP prion is the best-characterized prion, associated with neurodegenerative diseases such as Creutzfeldt-Jakob disease.
• Fungal prions, such as those in yeast, demonstrate that prion-like mechanisms can support stable, transmissible phenotypic states.
• Prions are not inherently pathogenic; they are ubiquitous and may play endogenous roles in cellular function.
• There is growing evidence that prion mechanisms contribute to evolutionary adaptation through epigenetic-like inheritance.
• The concept of prions as functional elements in evolution challenges the long-held view of prions as solely disease-causing agents.