A Camelid-derived Antibody Fragment Targeting the Active Site of a Serine Protease Balances between Inhibitor and Substrate Behavior.
J Biol Chem
; 291(29): 15156-68, 2016 07 15.
Article
en En
| MEDLINE
| ID: mdl-27226628
ABSTRACT
A peptide segment that binds the active site of a serine protease in a substrate-like manner may behave like an inhibitor or a substrate. However, there is sparse information on which factors determine the behavior a particular peptide segment will exhibit. Here, we describe the first x-ray crystal structure of a nanobody in complex with a serine protease. The nanobody displays a new type of interaction between an antibody and a serine protease as it inserts its complementary determining region-H3 loop into the active site of the protease in a substrate-like manner. The unique binding mechanism causes the nanobody to behave as a strong inhibitor as well as a poor substrate. Intriguingly, its substrate behavior is incomplete, as 30-40% of the nanobody remained intact and inhibitory after prolonged incubation with the protease. Biochemical analysis reveals that an intra-loop interaction network within the complementary determining region-H3 of the nanobody balances its inhibitor versus substrate behavior. Collectively, our results unveil molecular factors, which may be a general mechanism to determine the substrate versus inhibitor behavior of other protease inhibitors.
Palabras clave
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Camélidos del Nuevo Mundo
/
Serina Proteasas
/
Anticuerpos de Dominio Único
Tipo de estudio:
Prognostic_studies
Límite:
Animals
/
Humans
Idioma:
En
Año:
2016
Tipo del documento:
Article