title: The phosphatidyl-myo-inositol mannosyltransferase PimA is essential for Mycobacterium tuberculosis growth in vitro and in vivo.
abstract: The cell envelope of Mycobacterium tuberculosis contains glycans and lipids of peculiar structure that play prominent roles in the biology and pathogenesis of tuberculosis. Consequently, the chemical structure and biosynthesis of the cell wall have been intensively investigated in order to identify novel drug targets. Here, we validate that the function of phosphatidyl-myo-inositol mannosyltransferase PimA is vital for M. tuberculosis in vitro and in vivo. PimA initiates the biosynthesis of phosphatidyl-myo-inositol mannosides by transferring a mannosyl residue from GDP-Man to phosphatidyl-myo-inositol on the cytoplasmic side of the plasma membrane. To prove the essential nature of pimA in M. tuberculosis, we constructed a pimA conditional mutant by using the TetR-Pip off system and showed that downregulation of PimA expression causes bactericidality in batch cultures. Consistent with the biochemical reaction catalyzed by PimA, this phenotype was associated with markedly reduced levels of phosphatidyl-myo-inositol dimannosides, essential structural components of the mycobacterial cell envelope. In addition, the requirement of PimA for viability was clearly demonstrated during macrophage infection and in two different mouse models of infection, where a dramatic decrease in viable counts was observed upon silencing of the gene. Notably, depletion of PimA resulted in complete clearance of the mouse lungs during both the acute and chronic phases of infection. Altogether, the experimental data highlight the importance of the phosphatidyl-myo-inositol mannoside biosynthetic pathway for M. tuberculosis and confirm that PimA is a novel target for future drug discovery programs.
authors: Department of Molecular Medicine, University of Padua, Padua, Italy.
authors: Francesca
authors: F
authors: Boldrin
authors: Department of Molecular Medicine, University of Padua, Padua, Italy.
authors: Marcello
authors: M
authors: Ventura
authors: Department of Molecular Medicine, University of Padua, Padua, Italy.
authors: Giulia
authors: G
authors: Degiacomi
authors: AstraZeneca India Pvt. Ltd., Bangalore, India.
authors: Sudha
authors: S
authors: Ravishankar
authors: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors: Claudia
authors: C
authors: Sala
authors: Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
authors: Zuzana
authors: Z
authors: Svetlikova
authors: AstraZeneca India Pvt. Ltd., Bangalore, India.
authors: Anisha
authors: A
authors: Ambady
authors: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors: Neeraj
authors: N
authors: Dhar
authors: Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
authors: Jana
authors: J
authors: Kordulakova
authors: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors: Ming
authors: M
authors: Zhang
authors: Department of Molecular Medicine, University of Padua, Padua, Italy.
authors: Agnese
authors: A
authors: Serafini
authors: AstraZeneca India Pvt. Ltd., Bangalore, India.
authors: K G
authors: KG
authors: Vishwas
authors: AstraZeneca India Pvt. Ltd., Bangalore, India.
authors: V G
authors: VG
authors: Vishwas
authors: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors: Gaëlle S
authors: GS
authors: Kolly
authors: AstraZeneca India Pvt. Ltd., Bangalore, India.
authors: Naveen
authors: N
authors: Kumar
authors: Department of Molecular Medicine, University of Padua, Padua, Italy.
authors: Giorgio
authors: G
authors: Palù
authors: Unidad de Biofísica, Centro Mixto Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibertsitatea, Bizkaia, Spain Departamento de Bioquímica, Universidad del País Vasco, Bizkaia, Spain IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
authors: Marcelo E
authors: ME
authors: Guerin
authors: Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
authors: Katarina
authors: K
authors: Mikusova
authors: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors: Stewart T
authors: ST
authors: Cole
authors: Department of Molecular Medicine, University of Padua, Padua, Italy riccardo.manganelli@unipd.it.
authors: Riccardo
authors: R
authors: Manganelli
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology; D008364:Mannosyltransferases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D010716:Phosphatidylinositols / Q000096:biosynthesis; D014376:Tuberculosis / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D010716:Phosphatidylinositols; C034154:phosphatidylinositol mannoside; D008364:Mannosyltransferases; C543796:phosphatidyl-myo-inositol mannosyltransferase PimA, Mycobacterium smegmatis