title: Down-regulation of PE11, a cell wall associated esterase, enhances the biofilm growth of Mycobacterium tuberculosis and reduces cell wall virulence lipid levels.
abstract: PE11 (Rv1169c or LipX) is a cell wall associated esterase/lipase of Mycobacterium tuberculosis (Mtb). Evidences suggest that PE11 is expressed by Mtb both in vitro and in vivo. Previous studies have shown that PE11 leads to modification in cell wall lipid content and enhanced virulence when expressed in the non-pathogenic surrogate Mycobacterium smegmatis. Since cell wall lipids often play different roles in pathogenic and non-pathogenic mycobacteria, we investigated the role of PE11 in its host, Mtb. Mtb with lowered expression of PE11 (PE11 knock-down) displayed significant changes in colony morphology and cell wall lipid profile, confirming the role of PE11 in cell wall architecture. In addition, the levels of phthiocerol dimycocerosates, a cell wall virulence factor, were decreased. Levels of trehalose esters and free mycolic acids were increased. In contrast to M. smegmatis expressing Mtb PE11, a role reversal was observed in Mtb with respect to pellicle/biofilm formation. The PE11 knock-down Mtb strain showed significantly enhanced aggregation and early biofilm growth in detergent-free medium, compared to the wild-type. Knock-down strain also showed nearly 27-fold up-regulation of a fibronectin attachment protein (Rv1759c), linking biofilm growth with over-expression of bacterial proteins that help in aggregation and/or binding to host extracellular matrix. The knock-down also resulted in poor virulence of Mtb in PMA (phorbol 12-myristate 13-acetate) treated and PMA+IFN-γ treated THP-1 macrophages. Therefore, the study not only links PE11 to cell wall virulence lipids but also reveals the involvement of this cell wall associated esterase in down-regulation of biofilm in Mtb.
authors.affiliation: Division of Microbiology, Council of Scientific and Industrial Research, Central Drug Research Institute, Sitapur Road, Lucknow, Uttar Pradesh 226 031, India.
authors.forename: Shivangi
authors.initials: S
authors.lastname: Rastogi
authors.affiliation: Division of Molecular and Structural Biology, Council of Scientific and Industrial Research, Central Drug Research Institute, Sitapur Road, Lucknow, Uttar Pradesh 226 031, India.
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Sophisticated Analytical Instrument Facility, Council of Scientific and Industrial Research, Central Drug Research Institute, Sitapur Road, Lucknow, Uttar Pradesh 226 031, India.
authors.forename: Garima
authors.initials: G
authors.lastname: Pant
authors.affiliation: Sophisticated Analytical Instrument Facility, Council of Scientific and Industrial Research, Central Drug Research Institute, Sitapur Road, Lucknow, Uttar Pradesh 226 031, India.
authors.forename: Kalyan
authors.initials: K
authors.lastname: Mitra
authors.affiliation: Medicinal and Process Chemistry Division, Council of Scientific and Industrial Research, Central Drug Research Institute, Sitapur Road, Lucknow, Uttar Pradesh 226 031, India.
authors.forename: Koneni V
authors.initials: KV
authors.lastname: Sashidhara
authors.affiliation: Division of Microbiology, Council of Scientific and Industrial Research, Central Drug Research Institute, Sitapur Road, Lucknow, Uttar Pradesh 226 031, India.
authors.forename: Manju Y
authors.initials: MY
authors.lastname: Krishnan
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D002460:Cell Line; D002473:Cell Wall / Q000378:metabolism*; D004950:Esterases / Q000096:biosynthesis* / Q000235:genetics; D005353:Fibronectins / Q000378:metabolism; D055786:Gene Knockout Techniques; D006801:Humans; D008055:Lipids / Q000096:biosynthesis; D008264:Macrophages / Q000382:microbiology; D008563:Membrane Lipids / Q000378:metabolism*; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000472:pathogenicity; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D009171:Mycolic Acids / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014199:Trehalose / Q000378:metabolism; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005353:Fibronectins; D008055:Lipids; D008563:Membrane Lipids; D009171:Mycolic Acids; D037521:Virulence Factors; C008901:phthiocerol dimycocerosate; D014199:Trehalose; D004950:Esterases; C000623326:PE11 protein, Mycobacterium tuberculosis; D013755:Tetradecanoylphorbol Acetate