Proto-ubiquitin: Bayesian prediction of an ancient protein

Abstract

Ubiquitin (Ub) is a highly conserved protein that occurs only among eukaryotes. It labels proteins that are to be degraded by a multicatalytic protease complex involved in breaking down intracellular proteins. Bayesian statistics was employed to reconstruct the most plausible ancestral ubiquitin sequence of 30 extant species. Bioinformatics tools available online were used to characterize and compare ancestral and modem sequences. The putative ancestral sequence was 100% homologous with Ub of Brugia malayi. Compared to other extant species, among its 76 amino acids, only 9 residues have undergone changes. Therefore, no major structural and functional changes in the Ub were observed.