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Silva PA, Souza AA, de Oliveira GM, Ramada MHS, Hernández NV, Mora-Montes HM, Bueno RV, Martins-de-Sa D, de Freitas SM, Felipe MSS, Barbosa JARG. An improved expression and purification protocol enables the structural characterization of Mnt1, an antifungal target from Candida albicans. Fungal Biol Biotechnol 2024; 11:5. [PMID: 38715132 PMCID: PMC11077754 DOI: 10.1186/s40694-024-00174-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND Candida albicans is one of the most prevalent fungi causing infections in the world. Mnt1 is a mannosyltransferase that participates in both the cell wall biogenesis and biofilm growth of C. albicans. While the cell wall performs crucial functions in pathogenesis, biofilm growth is correlated with sequestration of drugs by the extracellular matrix. Therefore, antifungals targeting CaMnt1 can compromise fungal development and potentially also render Candida susceptible to drug therapy. Despite its importance, CaMnt1 has not yet been purified to high standards and its biophysical properties are lacking. RESULTS We describe a new protocol to obtain high yield of recombinant CaMnt1 in Komagataella phaffii using methanol induction. The purified protein's identity was confirmed by MALDI-TOF/TOF mass spectroscopy. The Far-UV circular dichroism (CD) spectra demonstrate that the secondary structure of CaMnt1 is compatible with a protein formed by α-helices and β-sheets at pH 7.0. The fluorescence spectroscopy results show that the tertiary structure of CaMnt1 is pH-dependent, with a greater intensity of fluorescence emission at pH 7.0. Using our molecular modeling protocol, we depict for the first time the ternary complex of CaMnt1 bound to its two substrates, which has enabled the identification of residues involved in substrate specificity and catalytic reaction. Our results corroborate the hypothesis that Tyr209 stabilizes the formation of an oxocarbenium ion-like intermediate during nucleophilic attack of the acceptor sugar, opposing the double displacement mechanism proposed by other reports. CONCLUSIONS The methodology presented here can substantially improve the yield of recombinant CaMnt1 expressed in flask-grown yeasts. In addition, the structural characterization of the fungal mannosyltransferase presents novelties that can be exploited for new antifungal drug's development.
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Affiliation(s)
- Patrícia Alves Silva
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, 70910-900, Brazil
| | - Amanda Araújo Souza
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, 70910-900, Brazil
| | - Gideane Mendes de Oliveira
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, 70910-900, Brazil
| | - Marcelo Henrique Soller Ramada
- Programa de Pós-graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, 70790-160, Brazil
| | - Nahúm Valente Hernández
- Departmento de Biologia, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, 36050, Mexico
| | - Héctor Manuel Mora-Montes
- Departmento de Biologia, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, 36050, Mexico
| | - Renata Vieira Bueno
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, 70910-900, Brazil
| | - Diogo Martins-de-Sa
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, 70910-900, Brazil
- Genesilico Biotech, Brasília, DF, Brazil
| | - Sonia Maria de Freitas
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, 70910-900, Brazil
| | - Maria Sueli Soares Felipe
- Programa de Pós-graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, 70790-160, Brazil
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