ABSTRACT
The microtubule motor kinesin-1 interacts via its cargo-binding domain with both microtubules and organelles, and hence plays an important role in controlling organelle transport and microtubule dynamics. In the absence of cargo, kinesin-1 is found in an autoinhibited conformation. The molecular basis of how cargo engagement affects the balance between kinesin-1's active and inactive conformations and roles in microtubule dynamics and organelle transport is not well understood. Here we describe the discovery of kinesore, a small molecule that in vitro inhibits kinesin-1 interactions with short linear peptide motifs found in organelle-specific cargo adaptors, yet activates kinesin-1's function of controlling microtubule dynamics in cells, demonstrating that these functions are mechanistically coupled. We establish a proof-of-concept that a microtubule motor-cargo interface and associated autoregulatory mechanism can be manipulated using a small molecule, and define a target for the modulation of microtubule dynamics.
Subject(s)
Enzyme Activators , Kinesins , Microtubules , Amino Acid Motifs , Enzyme Activators/chemistry , Enzyme Activators/pharmacology , HeLa Cells , Humans , Kinesins/chemistry , Kinesins/genetics , Kinesins/metabolism , Microtubules/chemistry , Microtubules/genetics , Microtubules/metabolismABSTRACT
Sortase A (SrtA) from Gram positive pathogens is an attractive target for inhibitors due to its role in the attachment of surface proteins to the cell wall. We found that the plant natural product trans-chalcone inhibits Streptococcus mutans SrtA in vitro and also inhibited S. mutans biofilm formation. Mass spectrometry revealed that the trans-chalcone forms a Michael addition adduct with the active site cysteine. The X-ray crystal structure of the SrtA H139A mutant provided new insights into substrate recognition by the sortase family. Our study suggests that chalcone flavonoids have potential as sortase-specific oral biofilm inhibitors.
