Construction and Characterization of a Brucella abortus mutant defective in Phospatydilethanolamine

BUKATTA, LUCAS; COMERCI, D; ALTABE, SILVIA GRACIELA; DE MENDOZA, D; UGALDE, R

Pinamar

Congreso; 41 th Annual Meeting. XLI.Reunión anual de la SAIB; 2005

SAIB

Brucella membrane is composed by three major lipids: phosphatidylethanolamine(PE), Phosphatidylcholine and Ornithine lipid. In bacteria, synthesis of PE occurs by condensation of CDP-diacylglycerol with serine to yield phosphatidylserine (PS), in a reaction catalyzed by PS synthase (pss). A subsequent PS decarboxilation produces PE. We are interested in studying the role that these lipids could play in the bacteria-host cell interaction. We have identified in the B. abortus genome a candidate gene coding for pss. The putative pss gene was cloned and knocked-out and the corresponding B. abortus pss mutant was generated. The lipid profile of the mutant indicated that it is devoid of PE. Although the viability of this mutant was not affected, its growth in TSB medium was diminished. However, millimolar concentration of Mg2+ restored the normal growth phenotype. The mutant’s capability to infect different in vitro cell cultures was severely affected.All the factors mentioned above will contribute to a better understanding of B. abortus ability to avoid the host’s immune defense and the establishment of a long-lasting infection.