REGULATION OF MYCOLIC ACIDS BIOSYNTHESIS IN MYCOBACTERIUM

VALENTINA SALZMAN; SONIA S MONDINO; GABRIELA GAGO; HUGO C GRAMAJO

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

The most relevant lipids present in cell envelope are the mycolic acids. These unusual fatty acids are essential for the survival and virulence of . However, there is no information about the regulation of the synthesis of these lipids, which involves two different fatty acid synthase (FAS) systems. Microarrays and quantitative proteomics studies revealed that inhibition of mycolate production by isoniazid (INH) induces transcription of the FASII components present in the operon. We found an ORF (Rv2242) upstream the operon with homology to transcriptional regulators. This ORF is present in all the actinomycetes genomes analyzed. Therefore, our working hypothesis is that this ORF, proposed to be essential, codes for a transcriptional regulator of mycolic acid synthesis. Rv2242 was successfully expressed and purified by affinity chromatography. Purified protein binds specifically to a 300-base pair fragment containing the promoter. Moreover, DnasaI footprinting analysis revealed the presence of an inverted repeat in the DNAbinding region that is conserved in all the actinomycetes promoters analyzed. This is the first report of the presence of a protein able to bind the operon promoter . We are currently studying the physiological role of this transcriptional regulator using M. smegmatis as a working model.