4-Hydroxyphenylpyruvate dioxygenase(HPPD)is an important target for both drug and pesticide discovery.As a typical Fe(II)-dependent dioxygenase,HPPD catalyzes the complicated transformation of 4-hydroxyphenylpyruvic a...4-Hydroxyphenylpyruvate dioxygenase(HPPD)is an important target for both drug and pesticide discovery.As a typical Fe(II)-dependent dioxygenase,HPPD catalyzes the complicated transformation of 4-hydroxyphenylpyruvic acid(HPPA)to homogentisic acid(HGA).The binding mode of HPPA in the catalytic pocket of HPPD is a focus of research interests.Recently,we reported the crystal structure of Arabidopsis thaliana HPPD(At HPPD)complexed with HPPA and a cobalt ion,which was supposed to mimic the pre-reactive structure of At HPPD-HPPA-Fe(II).Unexpectedly,the present study shows that the restored At HPPD-HPPA-Fe(II)complex is still nonreactive toward the bound dioxygen.QM/MM and QM calculations reveal that the HPPA resists the electrophilic attacking of the bound dioxygen by the trim of its phenyl ring,and the residue Phe381 plays a key role in orienting the phenyl ring.Kinetic study on the F381 A mutant reveals that the HPPD-HPPA complex observed in the crystal structure should be an intermediate of the substrate transportation instead of the pre-reactive complex.More importantly,the binding mode of the HPPA in this complex is shared with several well-known HPPD inhibitors,suggesting that these inhibitors resist the association of dioxygen(and exert their inhibitory roles)in the same way as the HPPA.The present study provides insights into the inhibition mechanism of HPPD inhibitors.展开更多
The insulin-degrading enzyme(IDE)plays a significant role in the degradation of the amyloid beta(Aβ),a peptide found in the brain regions of the patients with early Alzheimer’s disease.Adenosine triphosphate(ATP)all...The insulin-degrading enzyme(IDE)plays a significant role in the degradation of the amyloid beta(Aβ),a peptide found in the brain regions of the patients with early Alzheimer’s disease.Adenosine triphosphate(ATP)allosterically regulates the Aβ-degrading activity of IDE.The present study investigates the electrostatic interactions between ATP-IDE at the allosteric site of IDE,including thermostabilities/flexibilities of IDE residues,which have not yet been explored systematically.This study applies the quantum mechanics/molecular mechanics(QM/MM)to the proposed computational model for exploring electrostatic interactions between ATP and IDE.Molecular dynamic(MD)simulations are performed at different temperatures for identifying flexible and thermostable residues of IDE.The proposed computational model predicts QM/MM energy-minimised structures providing the IDE residues(Lys530 and Asp385)with high binding affinities.Considering root mean square fluctuation values during the MD simulations at 300.00 K including heat-shock temperatures(321.15 K and 315.15 K)indicates that Lys530 and Asp385 are also the thermostable residues of IDE,whereas Ser576 and Lys858 have high flexibilities with compromised thermostabilities.The present study sheds light on the phenomenon of biological recognition and interactions at the ATP-binding domain,which may have important implications for pharmacological drug design.The proposed computational model may facilitate the development of allosteric IDE activators/inhibitors,which mimic ATP interactions.展开更多
基金supported by the National Key R&D Program(No.2018YFD0200100)National Natural Science Foundation of China(Nos.21837001,21273089,22007035,U20A2038)+3 种基金the Open Project Fund of the Key Laboratory of the Pesticides and Chemical Biology of Central China Normal University(No.2018-A01)the Fundamental Research Funds for the South-Central University for Nationalities(No.CZW20020)the Fundamental Research Funds for the Central Universities(No.KJ02072020-0657)Hubei Province Natural Science Foundation(No.2020CFB487)。
文摘4-Hydroxyphenylpyruvate dioxygenase(HPPD)is an important target for both drug and pesticide discovery.As a typical Fe(II)-dependent dioxygenase,HPPD catalyzes the complicated transformation of 4-hydroxyphenylpyruvic acid(HPPA)to homogentisic acid(HGA).The binding mode of HPPA in the catalytic pocket of HPPD is a focus of research interests.Recently,we reported the crystal structure of Arabidopsis thaliana HPPD(At HPPD)complexed with HPPA and a cobalt ion,which was supposed to mimic the pre-reactive structure of At HPPD-HPPA-Fe(II).Unexpectedly,the present study shows that the restored At HPPD-HPPA-Fe(II)complex is still nonreactive toward the bound dioxygen.QM/MM and QM calculations reveal that the HPPA resists the electrophilic attacking of the bound dioxygen by the trim of its phenyl ring,and the residue Phe381 plays a key role in orienting the phenyl ring.Kinetic study on the F381 A mutant reveals that the HPPD-HPPA complex observed in the crystal structure should be an intermediate of the substrate transportation instead of the pre-reactive complex.More importantly,the binding mode of the HPPA in this complex is shared with several well-known HPPD inhibitors,suggesting that these inhibitors resist the association of dioxygen(and exert their inhibitory roles)in the same way as the HPPA.The present study provides insights into the inhibition mechanism of HPPD inhibitors.
文摘The insulin-degrading enzyme(IDE)plays a significant role in the degradation of the amyloid beta(Aβ),a peptide found in the brain regions of the patients with early Alzheimer’s disease.Adenosine triphosphate(ATP)allosterically regulates the Aβ-degrading activity of IDE.The present study investigates the electrostatic interactions between ATP-IDE at the allosteric site of IDE,including thermostabilities/flexibilities of IDE residues,which have not yet been explored systematically.This study applies the quantum mechanics/molecular mechanics(QM/MM)to the proposed computational model for exploring electrostatic interactions between ATP and IDE.Molecular dynamic(MD)simulations are performed at different temperatures for identifying flexible and thermostable residues of IDE.The proposed computational model predicts QM/MM energy-minimised structures providing the IDE residues(Lys530 and Asp385)with high binding affinities.Considering root mean square fluctuation values during the MD simulations at 300.00 K including heat-shock temperatures(321.15 K and 315.15 K)indicates that Lys530 and Asp385 are also the thermostable residues of IDE,whereas Ser576 and Lys858 have high flexibilities with compromised thermostabilities.The present study sheds light on the phenomenon of biological recognition and interactions at the ATP-binding domain,which may have important implications for pharmacological drug design.The proposed computational model may facilitate the development of allosteric IDE activators/inhibitors,which mimic ATP interactions.
