Staphylococcus aureus Exfoliative Toxin E, Oligomeric State and Flip of P186: Implications for Its Action Mechanism

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Gismene, Carolina ; Hernandez Gonzalez, Jorge Enrique ; Nino Santisteban, Angela Rocio ; Ziem Nascimento, Andrey Fabricio ; Cunha, Lucas dos Santos ; de Moraes, Fabio Rogerio ; Pinto de Oliveira, Cristiano Luis ; Oliveira, Caio C. ; Scarin Provazzi, Paola Jocelan ; Pascutti, Pedro Geraldo ; Arni, Raghuvir Krishnaswamy ; Mariutti, Ricardo Barros

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES; v. 23, n. 17, p. 20-pg., 2022-09-01.

Abstract

Staphylococcal exfoliative toxins (ETs) are glutamyl endopeptidases that specifically cleave the Glu381-Gly382 bond in the ectodomains of desmoglein 1 (Dsg1) via complex action mechanisms. To date, four ETs have been identified in different Staphylococcus aureus strains and ETE is the most recently characterized. The unusual properties of ETs have been attributed to a unique structural feature, i.e., the 180 degrees flip of the carbonyl oxygen (O) of the nonconserved residue 192/186 (ETA/ETE numbering), not conducive to the oxyanion hole formation. We report the crystal structure of ETE determined at 1.61 angstrom resolution, in which P186(O) adopts two conformations displaying a 180 degrees rotation. This finding, together with free energy calculations, supports the existence of a dynamic transition between the conformations under the tested conditions. Moreover, enzymatic assays showed no significant differences in the esterolytic efficiency of ETE and ETE/P186G, a mutant predicted to possess a functional oxyanion hole, thus downplaying the influence of the flip on the activity. Finally, we observed the formation of ETE homodimers in solution and the predicted homodimeric structure revealed the participation of a characteristic nonconserved loop in the interface and the partial occlusion of the protein active site, suggesting that monomerization is required for enzymatic activity. (AU)

• FAPESP's process: 20/08615-8 - Protein exosites, cryptic sites and moonlighting: identification, functional mapping and effects of changes in structure
• Grantee: Raghuvir Krishnaswamy Arni
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/10214-1 - Integrated computational and experimental strategies for the inhibition of exfoliative toxins from Staphylococcus aureus
• Grantee: Jorge Enrique Hernández González
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/07977-3 - Structural biology, mechanisms and inhibitory strategies of proteins involved in the pathogenic dissemination.
• Grantee: Ricardo Barros Mariutti
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 20/13921-0 - Structural determinants of necrotic and epidermolytic activity of exfoliative protein C (ExhC) of Staphylococcus sciuri
• Grantee: Carolina Gismene
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)