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Related Concept Videos

Epistasis Analysis01:09

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Although Mendel chose seven unrelated traits in peas to study gene segregation, most traits involve multiple gene interactions that create a spectrum of phenotypes. When the interaction of various genes or alleles at different locations influences a phenotype, this is called epistasis. Epistasis often involves one gene masking or interfering with the expression of another (antagonistic epistasis). Epistasis often occurs when different genes are part of the same biochemical pathway. The...
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Many proteins form complexes to carry out their functions, making protein-protein interactions (PPIs) essential for an organism's survival. Most PPIs are stabilized by numerous weak noncovalent chemical forces. The physical shape of the interfaces determines the way two proteins interact. Many globular proteins have closely-matching shapes on their surfaces, which form a large number of weak bonds. Additionally, many PPIs occur between two helices or between a surface cleft and a...
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In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
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Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex’s function. Often some of the proteins in the complex can be replaced by a closely related variant to give a complex that contains many of the same components yet is functionally distinct.
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Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues
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Strong epistatic interactions within a single protein.

Mariona Parera1, Miguel Angel Martinez2

  • 1Fundació irsiCaixa, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.

Molecular Biology and Evolution
|April 1, 2014
PubMed
Summary
This summary is machine-generated.

Intragenic epistasis influences protein evolution. A single amino acid change had varying fitness effects across different hepatitis C virus NS3 protease variants, demonstrating context-dependent contributions to protein function.

Keywords:
epistasisfitnessprotein evolution

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Area of Science:

  • Molecular Biology
  • Evolutionary Biology
  • Biochemistry

Background:

  • A key question in protein molecular evolution concerns whether amino acid mutations independently affect fitness or if their impact is modulated by other sites (intragenic epistasis).
  • If intragenic epistasis is absent, natural selection should act on mutations irrespective of the genetic background, yielding consistent fitness effects across different protein variants.

Purpose of the Study:

  • To investigate the role of intragenic epistasis in protein evolution.
  • To determine if a single amino acid substitution exhibits consistent fitness effects across diverse genetic backgrounds within the hepatitis C virus NS3 protease.

Main Methods:

  • Utilized site-directed mutagenesis to introduce a specific deleterious amino acid substitution into 56 distinct hepatitis C virus NS3 protease variants.
  • Assessed the catalytic efficiency of each mutated protease and compared it to its wild-type counterpart to quantify fitness effects.

Main Results:

  • The fitness effects of the introduced amino acid substitution varied significantly across the 56 tested variants, ranging from lethal to beneficial.
  • Primarily deleterious (41 variants) and lethal (5 variants) effects were observed, with fitness reductions spanning from -26.7% to -98.5%.

Conclusions:

  • The study provides strong evidence that the fitness impact of an amino acid substitution is dependent on the specific protein variant (genetic background).
  • These findings underscore the significant role of intragenic epistasis in shaping protein molecular evolution.