Genetic code ambiguity modulates the activity of a C. albicans MAP kinase linked to cell wall remodeling

Publication date: Available online 20 February 2019Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Joana S. Fraga, Zsuzsa Sárkány, Alexandra Silva, Inês Correia, Pedro José Barbosa Pereira, Sandra Macedo-RibeiroAbstractThe human fungal pathogen Candida albicans ambiguously decodes the universal leucine CUG codon predominantly as serine but also as leucine. C. albicans has a high capacity to survive and proliferate in adverse environments but the rate of leucine incorporation fluctuates in response to different stress conditions. C. albicans is adapted to tolerate this ambiguous translation through a mechanism that combines drastic decrease in CUG usage and reduction of CUG-encoded residues in conserved positions in the protein sequences. However, in a few proteins, the residues encoded by CUG codons are found in strictly conserved positions, suggesting that this genetic code alteration might have a functional impact. One such example is Cek1, a central signaling protein kinase that contains a single CUG-encoded residue at a conserved position, whose identity might regulate the correct flow of information across the MAPK cascade. Here we show that insertion of a leucine at the CUG-encoded position decreases the stability of Cek1, apparently without major structural alterations. In contrast, incorporation of a serine residue at the CUG position induces the autophosphorylation of the conserved tyrosine residue of the Cek1 231TEY233 motif, and ...
Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - Category: Biochemistry Source Type: research