title: Triacylglycerol utilization is required for regrowth of in vitro hypoxic nonreplicating Mycobacterium bovis bacillus Calmette-Guerin.
abstract: Mycobacteria store triacylglycerols (TGs) under various stress conditions, such as hypoxia, exposure to nitric oxide, and acidic environments. These stress conditions are known to induce nonreplicating persistence in mycobacteria. The importance of TG accumulation and utilization during regrowth is not clearly understood. Here we specifically determined the levels of accumulated TG and TG lipase activity in Mycobacterium bovis bacillus Calmette-Guerin (BCG) in various different physiological states (logarithmic growth, aerated stationary phase, hypoxia-induced dormancy, and regrowth from dormancy). We found extensive accumulation and degradation of TGs in the bacilli during entry into and exit from hypoxia-induced dormancy, respectively. These processes are accompanied by dynamic appearance and disappearance of intracellular TG lipid particles. The reduction in TG levels coincides with an increase in cellular TG lipase activity in the regrowing bacilli. Tetrahydrolipstatin, an inhibitor of TG lipases, reduces total lipase activity, prevents breakdown of TGs, and blocks the growth of mycobacteria upon resuscitation with air. Our results demonstrate that utilization of TGs is essential for the regrowth of mycobacteria during their exit from the hypoxic nonreplicating state.
authors.affiliation: NUS Graduate School for Integrative Sciences and Engineering (NGS), National University of Singapore, Singapore 117456, Republic of Singapore.
authors.forename: Kai Leng
authors.initials: KL
authors.lastname: Low
authors.forename: P S Srinivasa
authors.initials: PS
authors.lastname: Rao
authors.forename: Guanghou
authors.initials: G
authors.lastname: Shui
authors.forename: Anne K
authors.initials: AK
authors.lastname: Bendt
authors.forename: Kevin
authors.initials: K
authors.lastname: Pethe
authors.forename: Thomas
authors.initials: T
authors.lastname: Dick
authors.forename: Markus R
authors.initials: MR
authors.lastname: Wenk
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D007783:Lactones / Q000494:pharmacology; D008049:Lipase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D009163:Mycobacterium bovis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D000077403:Orlistat; D010100:Oxygen / Q000494:pharmacology; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D007783:Lactones; D014280:Triglycerides; D000077403:Orlistat; D008049:Lipase; D010100:Oxygen