RESUMO
Focal adhesion kinase (FAK) is a key mediator of tumour progression and metastasis. To date, clinical trials of FAK inhibitors have reported disappointing efficacy for oncology indications. We report the design and characterisation of GSK215, a potent, selective, FAK-degrading Proteolysis Targeting Chimera (PROTAC) based on a binder for the VHL E3 ligase and the known FAK inhibitor VS-4718. X-ray crystallography revealed the molecular basis of the highly cooperative FAK-GSK215-VHL ternary complex, and GSK215 showed differentiated in-vitro pharmacology compared to VS-4718. In mice, a single dose of GSK215 induced rapid and prolonged FAK degradation, giving a long-lasting effect on FAK levels (≈96â h) and a marked PK/PD disconnect. This tool PROTAC molecule is expected to be useful for the study of FAK-degradation biology inâ vivo, and our results indicate that FAK degradation may be a differentiated clinical strategy versus FAK inhibition for the treatment of cancer.
Assuntos
Antineoplásicos/farmacologia , Quinase 1 de Adesão Focal/antagonistas & inibidores , Proteólise/efeitos dos fármacos , Animais , Antineoplásicos/química , Antineoplásicos/farmacocinética , Benzamidas/química , Benzamidas/farmacocinética , Benzamidas/farmacologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Dipeptídeos/química , Dipeptídeos/farmacocinética , Dipeptídeos/farmacologia , Quinase 1 de Adesão Focal/metabolismo , Humanos , Camundongos , Estrutura Molecular , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Metabolic regulation occurs through precise control of enzyme activity. Allomorphy is a post-translational fine control mechanism where the catalytic rate is governed by a conformational switch that shifts the enzyme population between forms with different activities. ß-Phosphoglucomutase (ßPGM) uses allomorphy in the catalysis of isomerisation of ß-glucose 1-phosphate to glucose 6-phosphate via ß-glucose 1,6-bisphosphate. Herein, we describe structural and biophysical approaches to reveal its allomorphic regulatory mechanism. Binding of the full allomorphic activator ß-glucose 1,6-bisphosphate stimulates enzyme closure, progressing through NAC I and NAC III conformers. Prior to phosphoryl transfer, loops positioned on the cap and core domains are brought into close proximity, modulating the environment of a key proline residue. Hence accelerated isomerisation, likely via a twisted anti/C4-endo transition state, leads to the rapid predominance of active cis-P ßPGM. In contrast, binding of the partial allomorphic activator fructose 1,6-bisphosphate arrests ßPGM at a NAC I conformation and phosphoryl transfer to both cis-P ßPGM and trans-P ßPGM occurs slowly. Thus, allomorphy allows a rapid response to changes in food supply while not otherwise impacting substantially on levels of important metabolites.
Assuntos
Domínio Catalítico , Fosfoglucomutase , Prolina , Fosfoglucomutase/metabolismo , Fosfoglucomutase/química , Fosfoglucomutase/genética , Prolina/metabolismo , Prolina/química , Isomerismo , Glucofosfatos/metabolismo , Conformação Proteica , Humanos , Catálise , Modelos Moleculares , Glucose-6-Fosfato/análogos & derivadosRESUMO
The light-harvesting 2 complex (LH2) of the purple phototrophic bacterium Rhodobacter sphaeroides is a highly efficient, light-harvesting antenna that allows growth under a wide-range of light intensities. In order to expand the spectral range of this antenna complex, we first used a series of competition assays to measure the capacity of the non-native pigments 3-acetyl chlorophyll (Chl) a, Chlâ¯d, Chlâ¯f or bacteriochlorophyll (BChl) b to replace native BChlâ¯a in the B800 binding site of LH2. We then adjusted the B800 site and systematically assessed the binding of non-native pigments. We find that Arg-10 of the LH2 ß polypeptide plays a crucial role in binding specificity, by providing a hydrogen-bond to the 3-acetyl group of native and non-native pigments. Reconstituted LH2 complexes harbouring the series of (B)Chls were examined by transient absorption and steady-state fluorescence spectroscopies. Although slowed 10-fold to ~6â¯ps, energy transfer from Chlâ¯a to B850 BChlâ¯a remained highly efficient. We measured faster energy-transfer time constants for Chlâ¯d (3.5â¯ps) and Chlâ¯f (2.7â¯ps), which have red-shifted absorption maxima compared to Chlâ¯a. BChlâ¯b, red-shifted from the native BChlâ¯a, gave extremely rapid (≤0.1â¯ps) transfer. These results show that modified LH2 complexes, combined with engineered (B)Chl biosynthesis pathways in vivo, have potential for retaining high efficiency whilst acquiring increased spectral range.