Mycobacterium tuberculosis FasR senses long fatty acyl-CoA through a tunnel, inducing DNA-dissociation via a transmission spine

FELIPE TRAJTENBERG; MARISA M FERNÁNDEZ; BUSCHIAZZO A; LARA J; NICOLE LARRIEUX; GAGO GABRIELA; DIACOVICH LAUTARO; EMILIO L MALCHIODI ; GRAMAJO HUGO

NATURE COMMUNICATIONS

Nature Publishing Group

Lugar: Londres; Año: 2020 vol. 11 p. 1 - 13

2041-1723

Mycobacterium tuberculosis is a pathogen with a unique cell envelope including very long fatty acids, implicated in bacterial resistance and host immune modulation. FasR is a two-domain transcriptional activator that belongs to the TetR family of regulators, and plays a central role in mycobacterial longchainfatty acyl-CoA sensing and lipid biosynthesis regulation. We now disclose crystal structures of M. tuberculosis FasR in complex with acyl effector ligands and with DNA, uncovering its sensory and switching mechanisms. A long tunnel traverses the entire effector-binding domain, enabling long fatty acyl effectors to bind. Only when the tunnel is entirely occupied, the protein dimer adopts a rigid configuration, with its DNA-binding domains in an open state that leads to DNA dissociation. Structure-guided point-mutations further support this effector-dependent mechanism. The protein folding hydrophobic core, connecting the two domains, is completed by the effector ligand into a continuous spine, explaining the allosteric flexible-to-ordered transition. The transmission spine is conserved in all TetR-like transcription factors, offering new opportunities for anti-tuberculosis drug discovery.