| Human glutathione transferase A1-1 (hGSTA1-1) is a member of the alpha class of glutathione transferases (GSTs). Since this enzyme is implicated in important biological processes, such as cellular detoxification and drug-resistance, the molecular dynamics and functional properties of this enzyme are of great interest. NMR methods were applied to study the dynamic properties of hGSTA1-1. Backbone assignments were achieved for the perdeuterated unliganded hGSTA1-1, the protein complexed with a substrate, glutathione (GSH), and the protein complexed with a product of conjugation between glutathione and ethacrynic acid (EASG). Partial assignments for methyl groups were also obtained for the three forms of the protein. The behavior of the C-terminal helix of hGSTA1-1, which is unique for the alpha class enzymes, was studied. In the unliganded form, this part of the protein samples a number of helix-like structures. When GSH is bound, the C-terminal region forms a stable helix, with significant picosecond-nanosecond and millisecond timescale motions detected only at the ends. In the EASG-bound form, the helix is formed with no significant motion detected anywhere. Our results suggest that the dynamic behavior of the C-terminal region of hGSTA1-1 facilitates product release and contributes to enzymatic turnover.;The sar RNA is a small antisense RNA that regulates the translation of ant mRNA in the development of bacteriophage P22. NMR methods were applied to study the structural and dynamics properties of sar. sar RNA is 68–69 nucleotides in length and has been proposed to have two hairpins in its secondary structure. The separate hairpins were studied as well as the whole sar RNA. Partial assignments were achieved for the second hairpin of sar. Our studies show that the second hairpin of sar has a long well-defined double-helix stem, whether it is within the intact sar RNA or by itself. The first hairpin does not have a unique structure when the second hairpin is absent. However, it appears to have a well-defined structure within sar RNA. In addition, fragments of the ant mRNA were used to probe the sense-antisense pairing properties of sar and ant mRNA using NMR. |
