Amino acid substitutions around the chromophore of the chromoprotein Rtms5 influence polypeptide cleavage

• Published in: Biochemical and biophysical research communications Vol. 340; no. 4; pp. 1139 - 1143
• Main Authors: Turcic, Kristina, Pettikiriarachchi, Anne, Battad, Jion, Wilmann, Pascal G., Rossjohn, Jamie, Dove, Sophie G., Devenish, Rodney J., Prescott, Mark
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 24.02.2006
• Subjects: Acylimine bond; All-protein chromophores; Amino Acid Sequence; Amino Acid Substitution; Binding Sites; Chromoprotein; Computer Simulation; Luminescent Proteins - chemistry; Models, Chemical; Models, Molecular; Molecular Sequence Data; Peptides - chemistry; Protein Binding; Protein Conformation; Rtms5; Structure; Structure-Activity Relationship; Acylimine bond; Rtms5; Structure; All-protein chromophores; Chromoprotein
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.12.118

Extension of the conjugated π-system of many all-protein chromophores with an acylimine bond is the basis for their red-shifted optical properties. The presence of this post-translational modification is evident in crystal structures of these proteins. Harsh denaturation of proteins containing an acylimine bond results in partial polypeptide cleavage. For the red fluorescent protein DsRed, the extent of cleavage is quantitative. However, this is not the case for the blue non-fluorescent chromoprotein Rtms5, even though all chromophores in tetrameric Rtms5 contain an acylimine bond. We have identified two positions around the chromophore of Rtms5 where substitutions can promote or suppress the extent of cleavage on harsh denaturation. We propose a model in which cleavage of Rtms5 is facilitated by a trans to cis isomerisation of the chromophore.