Peptidomimetic inhibitors of human immunodeficiency virus-1 protease are successful lead substances for the development of virostatic drugs against HIV as the causative agent of acquired immunodeficiency syndrome (AIDS). The hydroxyethylamine isostere of the proteolytic cleavage intermediate provides a suitable replacement for the peptide bond. A series of acyclic pseudopeptide inhibitors with the hydroxyethylamine isostere varying in chiral carbon configuration and P'2 residue type were structurally analysed by single-crystal X-ray crystallography. The compounds inhibit HIV protease with subnanomolar inhibition constants and block viral replication in tissue cultures. Here, the structure of such a complex with the R configuration of the isosteric group (PDB code 1zsf) is presented together with newly available synchrotron data for a complex with the S stereoisomer of the inhibitor (PDB code 1zsr). Comparison of the structure and binding with other complexes of HIV-1 protease and similar inhibitors contributes to the understanding of how these molecules bind to the wild-type form of this enzyme. The hydroxy group of the R stereoisomer interacts with one of the catalytic aspartic acids by a short hydrogen bond with rather extreme geometry. The change of configuration of the chiral carbon bearing the hydroxyl from S to R does not influence the inhibition efficiency in this case.
- MeSH
- ethanolaminy chemie MeSH
- financování organizované MeSH
- HIV-1 enzymologie MeSH
- HIV-proteasa chemie metabolismus MeSH
- inhibitory HIV-proteasy chemie MeSH
- krystalografie rentgenová MeSH
- molekulární modely MeSH
- oligopeptidy chemie MeSH
- stereoizomerie MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- vodíková vazba MeSH
The X-ray structure of cold-active beta-galactosidase (isoenzyme C-2-2-1) from an Antarctic bacterium Arthrobacter sp. C2-2 was solved at 1.9A resolution. The enzyme forms 660 kDa hexamers with active sites opened to the central cavity of the hexamer and connected by eight channels with exterior solvent. To our best knowledge, this is the first cold-active beta-galactosidase with known structure and also the first known beta-galactosidase structure in the form of compact hexamers. The hexamer organization regulates access of substrates and ligands to six active sites and this unique packing, present also in solution, raises questions about its purpose and function. This enzyme belongs to glycosyl hydrolase family 2, similarly to Escherichia coli beta-galactosidase, forming tetramers necessary for its enzymatic function. However, we discovered significant differences between these two enzymes affecting the ability of tetramer/hexamer formation and complementation of the active site. This structure reveals new insights into the cold-adaptation mechanisms of enzymatic pathways of extremophiles.
- MeSH
- Arthrobacter enzymologie MeSH
- bakteriální proteiny genetika chemie metabolismus MeSH
- beta-galaktosidasa genetika chemie metabolismus MeSH
- financování organizované MeSH
- ionty chemie MeSH
- krystalografie rentgenová MeSH
- kvarterní struktura proteinů MeSH
- lidé MeSH
- molekulární modely MeSH
- molekulární sekvence - údaje MeSH
- nízká teplota MeSH
- rozpouštědla chemie MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
