The evolutionary consequences of erroneous protein synthesis

Abstract

Protein synthesis is a complex, multistage process, and many things can go wrong along the way. At present, our knowledge of protein-synthesis error rates is limited. But existing measurements indicate that protein synthesis is error prone in comparison with DNA replication. A protein that has not been synthesized correctly may be non-functional or toxic. However, it may also have a new, beneficial function. The synthesis of non-functional and toxic proteins imposes fitness costs on the organism. These costs generally increase with the expression level of a gene. Many mechanisms seem to have evolved to minimize the costs of erroneous protein synthesis. In some cases, organisms can take advantage of synthesis errors. For example, programmed frameshifts are sometimes used for expression regulation. Cellular life is an inherently noisy process. Every gene produces a range of different protein variants, and organisms optimize and take advantage of the properties of the entire range.