Paracoccidoides brasiliensis 30 kDa adhesin: identification as a 14-3-3 protein, cloning and subcellular localization in infection models

PLoS One. 2013 Apr 30;8(4):e62533. doi: 10.1371/journal.pone.0062533. Print 2013.

Abstract

Paracoccidoides brasiliensis adhesion to lung epithelial cells is considered an essential event for the establishment of infection and different proteins participate in this process. One of these proteins is a 30 kDa adhesin, pI 4.9 that was described as a laminin ligand in previous studies, and it was more highly expressed in more virulent P. brasiliensis isolates. This protein may contribute to the virulence of this important fungal pathogen. Using Edman degradation and mass spectrometry analysis, this 30 kDa adhesin was identified as a 14-3-3 protein. These proteins are a conserved group of small acidic proteins involved in a variety of processes in eukaryotic organisms. However, the exact function of these proteins in some processes remains unknown. Thus, the goal of the present study was to characterize the role of this protein during the interaction between the fungus and its host. To achieve this goal, we cloned, expressed the 14-3-3 protein in a heterologous system and determined its subcellular localization in in vitro and in vivo infection models. Immunocytochemical analysis revealed the ubiquitous distribution of this protein in the yeast form of P. brasiliensis, with some concentration in the cytoplasm. Additionally, this 14-3-3 protein was also present in P. brasiliensis cells at the sites of infection in C57BL/6 mice intratracheally infected with P. brasiliensis yeast cells for 72 h (acute infections) and 30 days (chronic infection). An apparent increase in the levels of the 14-3-3 protein in the cell wall of the fungus was also noted during the interaction between P. brasiliensis and A549 cells, suggesting that this protein may be involved in host-parasite interactions, since inhibition assays with the protein and this antibody decreased P. brasiliensis adhesion to A549 epithelial cells. Our data may lead to a better understanding of P. brasiliensis interactions with host tissues and paracoccidioidomycosis pathogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / analysis
  • 14-3-3 Proteins / genetics
  • 14-3-3 Proteins / metabolism*
  • Amino Acid Sequence
  • Animals
  • Cell Line
  • Cell Wall / chemistry
  • Cell Wall / metabolism
  • Cloning, Molecular
  • Epithelial Cells / microbiology
  • Epithelial Cells / pathology
  • Fungal Proteins / analysis
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Host-Pathogen Interactions*
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Paracoccidioides / cytology
  • Paracoccidioides / genetics
  • Paracoccidioides / pathogenicity*
  • Paracoccidioides / physiology*
  • Paracoccidioidomycosis / microbiology*
  • Paracoccidioidomycosis / pathology
  • Recombinant Proteins / analysis
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism

Substances

  • 14-3-3 Proteins
  • Fungal Proteins
  • Recombinant Proteins

Grants and funding

This investigation was financially supported by the Brazilian Organizations: FAPESP (Process Number 2011/18038-9), National Council for Scientific and Technological Development (Process number 473119/2010-2), PADCFCF-São Paulo State University and the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. JFS has a fellowship from Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior.