Dual virus-receptor duel

This study is unusual in that it involves a housekeeping gene that has been usurped for viral attachment. Evidence for positive selection of host genes can be detected by comparing gene sequences of phylogenetically related species. Nonsynonymous mutations lead to a change in the amino acid sequence, while synonymous mutations do not. The rate at which nonsynonymous mutations occur in the genome is typically much slower than synonymous mutations. The reason for this difference is that most mutations that change the amino acid sequence of a protein are lethal to the host. When genes have been subjected to positive selection by a virus, the ratio of nonsynonymous to synonymous mutations is higher, typically in host amino acids that interact with viral proteins. Computer programs have been designed to scan gene sequences and identify codons which are under positive selection by virtue of a high ratio of nonsynonymous to synonymous mutations. To determine if the transferrin receptor (TfR1) has evolved to prevent virus attachment, sequences of the protein from seven different rodent species were compared. The analysis revealed that much of the protein is highly conserved, but a small part, comprising six amino acids, is evolving rapidly. Three of these amino acids  are located on the part of TfR1 that binds arenaviruses, and three are at the binding site for the retrovirus mouse mammary tumor virus (MMTV) (see illustration). Changing these three amino acids of TfR1 of the house ...
Source: virology blog - Category: Virology Authors: Tags: Basic virology Information arenavirus evolution host-virus arms race iron mouse mammary tumor virus positive selection red queen conflict retrovirus transferrin receptor viral Source Type: blogs