title: PE is a functional domain responsible for protein translocation and localization on mycobacterial cell wall.
abstract: The PE family of Mycobacterium tuberculosis includes 98 proteins which share a highly homologous N-terminus sequence of about 110 amino acids (PE domain). Depending on the C-terminal domain, the PE family can be divided in three subfamilies, the largest of which is the PE_PGRS with 61 members. In this study, we determined the cellular localization of three PE proteins by cell fractionation and immunoelectron microscopy by expressing chimeric epitope-tagged recombinant proteins in Mycobacterium smegmatis. We demonstrate that the PE domain of PE_PGRS33 and PE11 (a protein constituted by the only PE domain) contains the information necessary for cell wall localization, and that they can be used as N-terminal fusion partners to deliver a sufficiently long C-terminus-linked protein domain on the mycobacterial cell surface. Indeed, we demonstrate that PE_PGRS33 and Rv3097c (a lipase belonging to the PE family) are surface exposed and localize in the mycobacterial cell wall. Moreover, we found that PE_PGRS33 is easily extractable by detergents suggesting its localization in the mycobacterial outer membrane. Beyond defining the cellular localization of these proteins, and a function for their PE domains, these data open the interesting possibility to construct recombinant mycobacteria expressing heterologous antigens on their surface for vaccine purposes.
authors.affiliation: Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, Padua, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cascioferro
authors.forename: Giovanni
authors.initials: G
authors.lastname: Delogu
authors.forename: Marisa
authors.initials: M
authors.lastname: Colone
authors.forename: Michela
authors.initials: M
authors.lastname: Sali
authors.forename: Annarita
authors.initials: A
authors.lastname: Stringaro
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Arancia
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fadda
authors.forename: Giorgio
authors.initials: G
authors.lastname: Palù
authors.forename: Riccardo
authors.initials: R
authors.lastname: Manganelli
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D002473:Cell Wall / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D019286:Endopeptidase K / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D019286:Endopeptidase K