Conformational analysis of Pneumococcal Surface Antigen A (PsaA) upon zinc binding by fluorescence spectroscopy

Conformational analysis of Pneumococcal Surface Antigen A (PsaA) upon zinc binding by fluorescence spectroscopy

PsaA (pneumococcal surface antigen A) is a S. pneumoniae virulence factor that belongs to the metal transport system. The Manganese PsaA binding has been associated with oxidative stress resistance becoming a pivotal element in the bacteria virulence. It has been shown that Zinc inhibits the Mangane...

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Bibliographic Details
Published in:Anais da Academia Brasileira de Ciências Vol. 90; no. 2 suppl 1; pp. 2299 - 2310
Main Authors: Bom, Ana Paula D Ano, Corrêa, Izabella B S, Argondizzo, Ana Paula C, Medeiros, Marco Alberto, Santos, Roger B Dos, Souza, Theo Luiz F de, Silva Junior, José G da
Format: Journal Article
Language:English
Published: Brazil Academia Brasileira de Ciências 01-08-2018
Subjects:
Adhesins, Bacterial - chemistry
Adhesins, Bacterial - drug effects
Antigens, Surface - chemistry
conformational analysis
Lipoproteins - chemistry
Lipoproteins - drug effects
MULTIDISCIPLINARY SCIENCES
Protein Conformation - drug effects
rPsaA
Spectrometry, Fluorescence
stability
Streptococcus Pneumoniae
Streptococcus pneumoniae - chemistry
Temperature
zinc
Zinc - pharmacology
rPsaA
conformational analysis
zinc
Streptococcus Pneumoniae
stability
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Summary:PsaA (pneumococcal surface antigen A) is a S. pneumoniae virulence factor that belongs to the metal transport system. The Manganese PsaA binding has been associated with oxidative stress resistance becoming a pivotal element in the bacteria virulence. It has been shown that Zinc inhibits the Manganese acquisition and promotes bacteria toxicity. We have performed a PsaA conformational analysis both in the presence (Zn-rPsaA) and in the absence of Zinc (free-rPsaA). We performed experiments in the presence of different Zinc concentrations to determine the metal minimum concentration which induced a conformational change. The protein in free and Zn-binding condition was also studied in pH ranging 2.6-8.0 and in temperature ranging 25oC-85oC. pH experiments showed a decrease of fluorescence intensity only in acidic medium. Analysis of the heat-induced denaturation demonstrated that Zinc-binding promoted an increase in melting temperature from 55oC (free-rPsaA) to 78.8oC (Zn-rPsaA) according to fluorescence measurements. In addition, the rPsaA stabilization by Zinc was verified through analysis of urea and guanidine hydrochloride denaturation. Data showed that Zinc promoted an increase in the rPsaA stability and its removal by EDTA can lead to a PsaA intermediate conformation. These findings can be considered in the development of vaccines containing PsaA as antigen.
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ISSN:0001-3765
1678-2690
1678-2690
DOI:10.1590/0001-3765201820170151