title: Crystal structure of Staphylococcus aureus exfoliative toxin D-like protein: Structural basis for the high specificity of exfoliative toxins.
abstract: Exfoliative toxins are serine proteases secreted by Staphylococcus aureus that are associated with toxin-mediated staphylococcal syndromes. To date, four different serotypes of exfoliative toxins have been identified and 3 of them (ETA, ETB, and ETD) are linked to human infection. Among these toxins, only the ETD structure remained unknown, limiting our understanding of the structural determinants for the functional differentiation between these toxins. We recently identified an ETD-like protein associated to S. aureus strains involved in mild mastitis in sheep. The crystal structure of this ETD-like protein was determined at 1.95 Å resolution and the structural analysis provide insights into the oligomerization, stability and specificity and enabled a comprehensive structural comparison with ETA and ETB. Despite the highly conserved molecular architecture, significant differences in the composition of the loops and in both the N- and C-terminal α-helices seem to define ETD-like specificity. Molecular dynamics simulations indicate that these regions defining ET specificity present different degrees of flexibility and may undergo conformational changes upon substrate recognition and binding. DLS and AUC experiments indicated that the ETD-like is monomeric in solution whereas it is present as a dimer in the asymmetric unit indicating that oligomerization is not related to functional differentiation among these toxins. Differential scanning calorimetry and circular dichroism assays demonstrated an endothermic transition centered at 52 °C, and an exothermic aggregation in temperatures up to 64 °C. All these together provide insights about the mode of action of a toxin often secreted in syndromes that are not associated with either ETA or ETB.
authors: Multi User Center for Biomolecular Innovation, Department of Physics, IBILCE/UNESP, São José do Rio Preto, SP, Brazil.
authors: Ricardo B
authors: RB
authors: Mariutti
authors: Carlos Chagas Institute, FIOCRUZ-PR, Curitiba, PR, Brazil.
authors: Tatiana A C B
authors: TA
authors: Souza
authors: Multi User Center for Biomolecular Innovation, Department of Physics, IBILCE/UNESP, São José do Rio Preto, SP, Brazil.
authors: Anwar
authors: A
authors: Ullah
authors: Multi User Center for Biomolecular Innovation, Department of Physics, IBILCE/UNESP, São José do Rio Preto, SP, Brazil.
authors: Icaro P
authors: IP
authors: Caruso
authors: Multi User Center for Biomolecular Innovation, Department of Physics, IBILCE/UNESP, São José do Rio Preto, SP, Brazil.
authors: Fábio R
authors: FR
authors: de Moraes
authors: Bioethanol Science and Technology Laboratory (CTBE), National Center for Research in Energy and Materials, Campinas, SP, 13083-970, Brazil.
authors: Leticia M
authors: LM
authors: Zanphorlin
authors: Cellular and Molecular Genetics Laboratory, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, 270-901, Brazil; INRA, UMR1253 STLO, Science et Technologie du Lait et de l'œuf, F-35042 Rennes, France; Agrocampus Ouest, UMR1253 STLO, F-35042 Rennes, France.
authors: Natayme R
authors: NR
authors: Tartaglia
authors: Cellular and Molecular Genetics Laboratory, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, 270-901, Brazil.
authors: Nubia
authors: N
authors: Seyffert
authors: Cellular and Molecular Genetics Laboratory, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, 270-901, Brazil.
authors: Vasco A
authors: VA
authors: Azevedo
authors: INRA, UMR1253 STLO, Science et Technologie du Lait et de l'œuf, F-35042 Rennes, France; Agrocampus Ouest, UMR1253 STLO, F-35042 Rennes, France.
authors: Yves
authors: Y
authors: Le Loir
authors: Brazilian Biosciences National Laboratory (LNBio), National Center for Research in Energy and Materials, Campinas, SP, 13083-970, Brazil.
authors: Mário T
authors: MT
authors: Murakami
authors: Multi User Center for Biomolecular Innovation, Department of Physics, IBILCE/UNESP, São José do Rio Preto, SP, Brazil. Electronic address: arni@sjrp.unesp.br.
authors: Raghuvir K
authors: RK
authors: Arni
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D005083:Exfoliatins / Q000737:chemistry* / Q000145:classification / Q000633:toxicity*; D005260:Female; D006801:Humans; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D012756:Sheep; D013203:Staphylococcal Infections / Q000209:etiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000472:pathogenicity*; D055672:Static Electricity; D040681:Structural Homology, Protein; D013577:Syndrome
chemical_list: D005083:Exfoliatins
keywords: Crystal structure; Exfoliative toxin D-like protein; Staphylococcus aureus; Toxin-mediated staphylococcal syndromes