title: Genome and transcriptome scale portrait of sigma factors in Mycobacterium avium subsp. paratuberculosis.
abstract: Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of Johne's disease (JD), a chronic gastroenteritis of ruminants and other animals, including primates. Many evidences suggested association of MAP to Crohn's disease, a chronic granulomatous gastrointestinal disease of humans with strong similarities with JD. The present study attempts to evaluate global gene regulation in MAP, which has not been addressed previously, despite the availability of MAP genome sequence. For this purpose, we investigated: (i) the presence of sigma factors and their relationship to sigma factors of other mycobacteria (M. avium subsp.avium, M. tuberculosis, M. bovis, M. leprae and M. smegmatis), and (ii) their expression during different growth conditions and in vitro infection of intestinal epithelial Caco2 cells. MAP genome contains 19 putative sigma factor, but only 12 belong to gene families common to other mycobacteria. Gene expression was evaluated with Real-Time PCR during growth in 7H9 medium and mycobactin J, in 7H9 medium plus mycobactin J and lisozyme, and during infection of Caco2 cells: very different expression patterns were observed and, on the whole, only 7 sigma factors were found to be expressed. sigJ was upregulated during the infection of Caco2 cells. Even if only few sigma factors were expressed in the three conditions tested, the overall high numbers of MAP sigma factors suggests a noteworthy flexibility of this pathogen. Thus, this first report on expression of MAP sigma factors opens the way to an extensive characterization of global gene regulation, as a key to understand strategies of survival and mechanisms of infections used by this organism.
authors.affiliation: Dipartimento di Scienze Biomediche, Sezione di Microbiologia Sperimentale e Clinica, Università degli studi di Sassari, Viale S. Pietro 43/B, 07100 Sassari, Italy. schila@uniss.it
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Sechi
authors.forename: Giovanna E
authors.initials: GE
authors.lastname: Felis
authors.forename: Niyaz
authors.initials: N
authors.lastname: Ahmed
authors.forename: Daniela
authors.initials: D
authors.lastname: Paccagnini
authors.forename: Donatella
authors.initials: D
authors.lastname: Usai
authors.forename: Silvia
authors.initials: S
authors.lastname: Ortu
authors.forename: Paola
authors.initials: P
authors.lastname: Molicotti
authors.forename: Stefania
authors.initials: S
authors.lastname: Zanetti
mesh_terms: D018938:Caco-2 Cells; D004847:Epithelial Cells / Q000187:drug effects / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D016680:Genome, Bacterial / Q000235:genetics*; D006801:Humans; D007422:Intestines / Q000166:cytology / Q000187:drug effects / Q000382:microbiology; D009113:Muramidase / Q000378:metabolism; D009162:Mycobacterium avium / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D016927:Mycobacterium avium subsp. paratuberculosis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D010080:Oxazoles / Q000494:pharmacology; D010802:Phylogeny; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D010080:Oxazoles; D012808:Sigma Factor; C018608:mycobactins; D009113:Muramidase