STRUCTURAL STUDY OF THE TRANSCRIPTIONAL REGULATORS MabR AND FasR FROM Mycobacterium tuberculosis: CONTROL OF FATTY ACID BIOSYNTHESIS AND LIPID HOMEOSTASIS

LARA L, DIACOVICH L, LARRIEUX N, BUSCHIAZZO A, GAGO G, GRAMAJO H

Córdoba

Congreso; IX Reunión Anual de la AACr y I Reunión Latinoamericana de Cristalografía; 2013

Asociación Argentina de Cristalografía

Mycolic acids (MA) present at the cell wall of M. tuberculosis play an important role in its architecture, impermeability and antibiotic exclusion of this human pathogen. Mycobacteria, unlike most bacteria, have two fatty acid synthases (FAS-I and FAS-II) [1] which work in concert to synthetize MA. Our research group identified two transcriptional regulators essential for mycobacterial viability, involved in the regulatory network of fatty acids biosynthesis. MabR, which controls the expression of fasII operon genes by binding to the fasII promoter region, and FasR, which specifically binds to fas promoter region and controls the de novo fatty acid biosynthesis [2,3]. I order to deeply characterize the molecular bases of MabR and FasR interaction with their corresponding DNA targets, we performed experiments to obtain the crystal structures of both transcriptional regulators. Both proteins were screened based on sitting drop vapor diffusion. Laminar crystals of His-MabR were obtained, although not suitable for structural determination. Then, we explored new crystallization conditions using the native protein (without His6-tag) and found rod-like crystals in the presence of the DNA interacting probe. Additionally, we recently established conditions where small crystals of FasR native protein were obtained. Currently, we are optimizing the crystallization conditions for both proteins in order to obtain diffraction data. The structural characterization of these novel transcriptional regulators might provide significant information for the development of conceptually new antimycobacterium compounds.