Impact of the deletion of the six mce operons in Mycobacterium smegmatis

LAURA I. KLEPP Y MARINA A. FORRELLAD; ANA V. OSELLA; FEDERICO BLANCO; EMMA J. STELLA; MARÍA VERÓNICA BIANCO; MARÍA DE LA PAZ SANTANGELO; CRISTOPHER SASSETTI; MARY JACKSON; ANGEL A. CATALDI; FABIANA BIGI; HÉCTOR R. MORBIDONI

MICROBES AND INFECTION

ELSEVIER SCIENCE BV

Año: 2012

1286-4579

The Mycobacterium smegmatis genome contains six operons designated mce (mammalian cell entry). These operons, which encodemembrane and exported proteins, are highly conserved in pathogenic and non-pathogenic mycobacteria. Although the function of the Mceprotein family has not yet been established in Mycobacterium smegmatis, the requirement of the mce4 operon for cholesterol utilization anduptake by Mycobacterium tuberculosis has recently been demonstrated. In this study, we report the construction of an M. smegmatis knock-outmutant deficient in the expression of all six mce operons. The consequences of these mutations were studied by analyzing physiologicalparameters and phenotypic traits. Differences in colony morphology, biofilm formation and aggregation in liquid cultures were observed,indicating that mce operons of M. smegmatis are implicated in the maintenance of the surface properties of the cell. Importantly, the mutantstrain showed reduced cholesterol uptake when compared to the parentalstrain. Further cholesterol uptake studies using single mce mutant strainsshowed that the mutation of operon mce4 was reponsible for the cholesterol uptake failure detected in the sextuple mce mutant. This findingdemonstrates that mce4 operon is involved in cholesterol transport in M. smegmatis.