Crystal structure and molecular dynamics studies of human purine nucleoside phosphorylase complexed with 7-deazaguanine.
In humans, purine nucleoside phosphorylase (HsPNP) is responsible for degradation of deoxyguanosine, and genetic deficiency of this enzyme leads to profound T-cell mediated immunosuppression. HsPNP is a target for inhibitor development aiming at T-cell immune response modulation. Here we report the crystal structure of HsPNP in complex with 7-deazaguanine (HsPNP:7DG) at 2.75 A. Molecular dynamics simulations were employed to assess the structural features of HsPNP in both free form and in complex with 7DG. Our results show that some regions, responsible for entrance and exit of substrate, present a conformational variability, which is dissected by dynamics simulation analysis. Enzymatic assays were also carried out and revealed that 7-deazaguanine presents a lower inhibitory activity against HsPNP (K(i)=200 microM). The present structure may be employed in both structure-based design of PNP inhibitors and in development of specific empirical scoring functions.
Caceres
Rafael Andrade
RA
Faculdade de Biociências, Instituto Nacional de Ciência e Tecnologia em Tuberculose-CNPq, Laboratório de Bioquímica Estrutural, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, RS, Brazil.
Timmers
Luis Fernando Saraiva Macedo
LF
Pauli
Ivani
I
Gava
Lisandra Marques
LM
Ducati
Rodrigo Gay
RG
Basso
Luiz Augusto
LA
Santos
Diógenes Santiago
DS
de Azevedo
Walter Filgueira
WF
D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D025341:Principal Component Analysis; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011683:Purine-Nucleoside Phosphorylase / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014961:X-Ray Diffraction / Q000379:methods*
D006147:Guanine; D011683:Purine-Nucleoside Phosphorylase; C066856:7-deazaguanine