title: A secreted serine protease of Paracoccidioides brasiliensis and its interactions with fungal proteins.
abstract: BACKGROUND
  Paracoccidioides brasiliensis is a thermodimorphic fungus, the causative agent of paracoccidioidomycosis (PCM). Serine proteases are widely distributed and this class of peptidase has been related to pathogenesis and nitrogen starvation in pathogenic fungi.
  
  
  RESULTS
  A cDNA (Pbsp) encoding a secreted serine protease (PbSP), was isolated from a cDNA library constructed with RNAs of fungal yeast cells recovered from liver of infected mice. Recombinant PbSP was produced in Escherichia coli, and used to develop polyclonal antibodies that were able to detect a 66 kDa protein in the P. brasiliensis proteome. In vitro deglycosylation assays with endoglycosidase H demonstrated that PbSP is a N-glycosylated molecule. The Pbsp transcript and the protein were induced during nitrogen starvation. The Pbsp transcript was also induced in yeast cells infecting murine macrophages. Interactions of PbSP with P. brasiliensis proteins were evaluated by two-hybrid assay in the yeast Saccharomyces cerevisiae. PbSP interacts with a peptidyl prolyl cis-trans isomerase, calnexin, HSP70 and a cell wall protein PWP2.
  
  
  CONCLUSIONS
  A secreted subtilisin induced during nitrogen starvation was characterized indicating the possible role of this protein in the nitrogen acquisition. PbSP interactions with other P. brasiliensis proteins were reported. Proteins interacting with PbSP are related to folding process, protein trafficking and cytoskeleton reorganization.
authors.affiliation: Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.
authors.forename: Juliana A
authors.initials: JA
authors.lastname: Parente
authors.forename: Sílvia M
authors.initials: SM
authors.lastname: Salem-Izacc
authors.forename: Jaime M
authors.initials: JM
authors.lastname: Santana
authors.forename: Maristela
authors.initials: M
authors.lastname: Pereira
authors.forename: Clayton L
authors.initials: CL
authors.lastname: Borges
authors.forename: Alexandre M
authors.initials: AM
authors.lastname: Bailão
authors.forename: Célia M A
authors.initials: CM
authors.lastname: Soares
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005260:Female; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010228:Paracoccidioides / Q000201:enzymology* / Q000235:genetics; D010229:Paracoccidioidomycosis / Q000382:microbiology*; D011485:Protein Binding; D021381:Protein Transport; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D057057:Serine Proteases