Investigation of structural factors controlling loop dynamics in acyl protein thioesterases

Abstract

FTT258 is a close bacterial relative of human acyl protein thioesterases (APTs). Human APTs catalyze the depalmitoylation of key signaling proteins attached to the plasma membrane. For FTT258, catalysis was hypothesized to be regulated by the large‐scale movement of an essential dynamic loop, which transitioned the protein between active and inactive states. However, the causes for the movement of this loop are unknown. Herein, we investigated factors that trigger loop movement in APTs like FTT258. In particular, FTT258 was exposed to inhibitors structurally similar to long chain lipids and to membrane‐mimicking surfactants to determine if these factors induce loop movement. Loop movement was detected by measuring the change in intrinsic tryptophan fluorescence of a central tryptophan on the dynamic loop before and after exposure to these conditions. Although inhibitors and substrate mimics induced minor changes in loop dynamics, larger shifts were measured with various membrane‐mimicking surfactants, suggesting that APT loop dynamics are mainly regulated by proximity to the plasma membrane. Ultimately, understanding the factors controlling APT function could provide novel mechanisms for controlling cell signaling.Support or Funding InformationFunded by NSF MCB‐1812971This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.