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Amide hydrogen exchange in HIV –1 subtype B and C proteases – insights into reduced drug susceptibility and dimer stability
Author(s) -
Naicker Previn,
Stoychev Stoyan,
Dirr Heini W.,
Sayed Yasien
Publication year - 2014
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13084
Subject(s) - proteases , protease , darunavir , hiv 1 protease , chemistry , hydrogen–deuterium exchange , enzyme , biochemistry , human immunodeficiency virus (hiv) , virology , biology , mass spectrometry , viral load , antiretroviral therapy , chromatography
Since its identification, HIV has continued to have a detrimental impact on the lives of millions of people throughout the world. The protease of HIV is a major target in antiviral treatment. The South African HIV –1 subtype C (C– SA ) protease displays weaker binding affinity for some clinically approved protease inhibitors in comparison with the HIV –1 subtype B protease. The heavy HIV burden in sub‐Saharan Africa, where subtype C HIV –1 predominates, makes this disparity a topic of great interest. In light of this, the enzyme activity and affinity of protease inhibitors for the subtype B and C– SA proteases were determined. The relative vitality, indicating the selective advantage of polymorphisms, of the C– SA protease relative to the subtype B protease in the presence of ritonavir and darunavir was four‐ and tenfold greater, respectively. Dynamic differences that contribute to the reduced drug susceptibility of the C– SA protease were investigated by performing hydrogen–deuterium exchange/mass spectrometry ( HDX / MS ) on unbound subtype B and C– SA proteases. The reduced propensity to form the E35–R57 salt bridge, and alterations in the hydrophobic core of the C– SA protease, are proposed to affect the anchoring of the flexible flaps, resulting in an increased proportion of the fully open flap conformation. HDX / MS data suggested that the N–terminus of both proteases is less stable than the C–terminus of the proteases, thus explaining the increased efficacy of dimerization inhibitors targeted toward the C–terminus of HIV proteases. As far as we are aware, this is the first report on assessment of HIV protease dynamics using HDX / MS .