Amino acid substitutions around the chromophore of the chromoprotein Rtms5 influence polypeptide cleavage.
Extension of the conjugated pi-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.
Turcic
Kristina
K
The Protein Crystallography Unit, Monash Centre for Synchrotron Science, Monash University, Clayton Campus, Vic. 3800, Australia.
Pettikiriarachchi
Anne
A
Battad
Jion
J
Wilmann
Pascal G
PG
Rossjohn
Jamie
J
Dove
Sophie G
SG
Devenish
Rodney J
RJ
Prescott
Mark
M
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D003198:Computer Simulation; D008164:Luminescent Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship
D008164:Luminescent Proteins; D010455:Peptides