Directed evolution of this construct now shows a drastic reorganization of the active site to use an alternative catalytic lysine and suggests considerations for future design efforts.
The midpoint of thermal denaturation monitored by circular dichroism, ranges between 59 and 80 °C, compared to 66 °C for the two wild-type enzymes, indicating that the chimeric enzymes adopt a stable folded structure and that the observed reductions in catalytic efficiency are due to reorganization of the active site.
The structure of the double mutant shows how catalytic competency is maintained despite spatial reorganization of the active site with respect to substrate.
In the framework of TST, the enzyme needs to reduce the energy barrier for the reaction via electrostatic pre- or reorganization of the active site, moving toward stabilization of the reaction's TS.
Engaging the α-exosite, we surmise, causes the protease tertiary structure to undergo a subtle conformational change resulting in a reorganization of the active site with the net result of increased catalysis.
Because genome-wide analysis of EMT has revealed that TGF β induces global reorganization of transcriptionally active marks (histone (H3) Lys (K) 36 trimethyl) in large organized heterochromatin domains [ 20], we examined whether the NF- κB-dependent genes were affected by chromatin remodeling or via changes in transcriptional elongation.
Furthermore, the heat capacity changes (Δ C p °) associated with the ligand binding to HDAC8 markedly differed from one SAHA analogue to the other, and such features could primarily be rationalized in light of the dynamic flexibility in the enzyme structure in conjunction with the reorganization of the active site resident water molecules.
In vivo experiments with GFP fusions showed that the N-terminal region of ForC targets the protein to places of active actin reorganization, like macropinosomes, phagocytic cups and cell-to-cell contacts [ 20].
Alternatively, early formation of HP1β foci may be indicative of active chromatin reorganization in a manner similar to the one observed during the final rounds or replication that precede cell cycle exit triggered by nutrient deprivation or after contact inhibition (Barbie et al., 2004).
Fonseca, A. V., Freund, D., Bornhaeuser, M. & Corbeil, D. Polarization and migration of hematopoietic stem and progenitor cells rely on the RhoA/ROCK I pathway and an active reorganization of the microtubule network.
