Kinetics of Aspartimide Formation and Hydrolysis in Lasso Peptide Lihuanodin.
Biochemistry
; 62(3): 695-699, 2023 02 07.
Article
em En
| MEDLINE
| ID: mdl-36701287
ABSTRACT
Aspartimides are notorious as undesired side products in solid-phase peptide synthesis and in pharmaceutical formulations. However, we have discovered several ribosomally synthesized and post-translationally modified peptides (RiPPs) in which aspartimide is installed intentionally via enzymatic activity of protein l-isoaspartyl methyltransferase (PIMT) homologues. In the case of the lasso peptide lihuanodin, the methyltransferase LihM recognizes the lassoed substrate pre-lihuanodin, specifically methylating the side chain of an l-Asp residue in the ring portion of the lasso peptide. The subsequent nucleophilic attack from the adjacent amide leads to the formation of an aspartimide. The resulting aspartimide hydrolyzes regioselectively to l-Asp in buffers above pH 7. Here we report the first Michaelis-Menten kinetic measurements of such a RiPP-associated PIMT homologue, LihM, acting on its cognate substrate pre-lihuanodin. Additionally, we measured the rate of aspartimide hydrolysis, which allowed us to deduce the kinetics of the entire reaction network. The relative magnitudes of these rates explain the accumulation and relative stability of aspartimide-containing lihuanodin. We also demonstrate that the residue C-terminal to the aspartimide controls the regioselectivity of hydrolysis and thus the threadedness of the peptide.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
/
Ácido Aspártico
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Estados Unidos