S16 and T18 mannosylation sites of LppX are not essential for its activity in phthiocerol dimycocerosates localization at the surface of Mycobacterium tuberculosis

Cécile Labarre (1) , Nathalie Dautin (1, 2) , Anna Grzegorzewicz , Mary Jackson , Michael Mcneil , Niloofar Mohiman (1) , Laila Sago (1) , Nicolas Bayan (1)

1 I2BC - Institut de Biologie Intégrative de la Cellule
2 LBPC-PM (UMR_7099) - Laboratoire de biologie physico-chimique des protéines membranaires

LppX is an important virulence factor essential for surface localization of phthiocerol dimycocerosates (DIM) in Mycobacterium tuberculosis. Based on Concanavalin A recognition, M. tuberculosis LppX (LppX-tb) was initially proposed to be glycosylated in M. tuberculosis and more recently this glycosylation was characterized by mass spectrometry analysis on LppX-tb expressed and purified from Corynebacterium glutamicum. Here, using this model organism and Mycobacterium smegmatis, we show that S16 and T18 residues of LppX-tb are indeed glycosylated with several hexoses units. Interestingly this glycosylation is strictly dependent on the mannosyl transferase PMT which, in M. tuberculosis, has been reported to be crucial for virulence. Using a site directed mutagenesis approach, we were able to show that the absence of S16 and T18 glycosylation does not alter phthiocerol dimycocerosates (DIM) localization in M. tuberculosis.

Mots clés: Corynebacterium glutamicum; Mycobacterium; glycosylation; phthiocerol dimycocerosates

Domaines: Biologie moléculaire

Cécile Labarre, Nathalie Dautin, Anna Grzegorzewicz, Mary Jackson, Michael Mcneil, et al.. S16 and T18 mannosylation sites of LppX are not essential for its activity in phthiocerol dimycocerosates localization at the surface of Mycobacterium tuberculosis. Research in Microbiology, In press, ⟨10.1016/j.resmic.2021.103874⟩. ⟨hal-03389123⟩