Functional Characterization of Bacillus sp. Acyl-lipid desaturase

ALEMANY, MARIANA; DE MENDOZA, D; ALTABE, SILVIA GRACIELA

Villa Carlos Paz. Cordoba.Argentina

Congreso; XLIV Reunión anual de SAIB.; 2008

SAIB

The biosynthesis of unsaturated fatty acids is carried out by desaturases, a family of enzymes that introduces a double bond at specific positions in fatty acids and play an important role in determining the fluidity of cell membranes. Knowledge about the determinants of their enzymatic specificity is still not understood.Our main goal is to understand the specific role of amino acid residues in substrate recognition and double bond-positioning activities of desaturases. In silico analysis on Bacillus genomes allowed us the identification of highly similar desaturases. We have characterized two desaturases from B. licheniformis and two from B. cereus. It was done by expressing them in B. sutilis des mutant and analysing the fatty acids patterns by GC-MS. B. licheniformis BLO2106 and B. cereus BC2983 are Ä5-desaturases, 70-71 % identical to B. subtilis orthologous. B. cereus BC0400 is a Ä10-desaturase and BLO2692 did not present activity. Site-directed mutagenesis and domain swapping techniques will help us to elucidate which residues or regions in these enzymes that are important for the substrate specificity and/or regioselectivity.