title: Structural basis of lipid biosynthesis regulation in Gram-positive bacteria.
abstract: Malonyl-CoA is an essential intermediate in fatty acid synthesis in all living cells. Here we demonstrate a new role for this molecule as a global regulator of lipid homeostasis in Gram-positive bacteria. Using in vitro transcription and binding studies, we demonstrate that malonyl-CoA is a direct and specific inducer of Bacillus subtilis FapR, a conserved transcriptional repressor that regulates the expression of several genes involved in bacterial fatty acid and phospholipid synthesis. The crystal structure of the effector-binding domain of FapR reveals a homodimeric protein with a thioesterase-like 'hot-dog' fold. Binding of malonyl-CoA promotes a disorder-to-order transition, which transforms an open ligand-binding groove into a long tunnel occupied by the effector molecule in the complex. This ligand-induced modification propagates to the helix-turn-helix motifs, impairing their productive association for DNA binding. Structure-based mutations that disrupt the FapR-malonyl-CoA interaction prevent DNA-binding regulation and result in a lethal phenotype in B. subtilis, suggesting this homeostatic signaling pathway as a promising target for novel chemotherapeutic agents against Gram-positive pathogens.
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR), Universidad Nacional de Rosario, Rosario, Argentina.
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Schujman
authors.forename: Marcelo
authors.initials: M
authors.lastname: Guerin
authors.forename: Alejandro
authors.initials: A
authors.lastname: Buschiazzo
authors.forename: Francis
authors.initials: F
authors.lastname: Schaeffer
authors.forename: Leticia I
authors.initials: LI
authors.lastname: Llarrull
authors.forename: Georgina
authors.initials: G
authors.lastname: Reh
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Vila
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Alzari
authors.forename: Diego
authors.initials: D
authors.lastname: de Mendoza
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D008055:Lipids / Q000096:biosynthesis*; D008316:Malonyl Coenzyme A / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D008055:Lipids; D012097:Repressor Proteins; D008316:Malonyl Coenzyme A