Rieske proteins have a pH-dependent reduction potential, which has been postulated to depend on the solvent accessibility of the two ligating histidines, the number of hydrogen bonds to the cluster, and the proximity of charged residues to the cluster. To study these factors, mutations to Y158, G156 and L135 of Thermus thermophilus Rieske protein were made. Crystallographic studies of Y158F at 1.85 � show little change to the structure with the removal of the hydrogen bond to the ligating Cys. G156S adds a hydrogen bond to the S* of the [2Fe-2S] cluster, resulting in an increased reduction potential.  Evidence for the increase includes a visible spectrum resembling reduced protein, lack of reactivity toward diethyl pyrocarbonate, and oxidization by K3Fe(CN)6.  L135A alters the solvent exposure of the histidines and X-ray crystal data was collected to 2.3 �. The X-ray crystal structures of the L135R and L135E, designed to add a positive or negative charge adjacent to the cluster respectively, have also been collected and refined at 1.85 � and 2.5 � resolution respectively.

Biochemical and structural study probing the effects of mutations to the [2Fe-2S] cluster of <i>Thermus thermophilus</i> Rieske protein

243rd National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Biochemical and structural study probing the effects of mutations to the [2Fe-2S] cluster of Thermus thermophilus Rieske protein