Marco, Salvatore (2013) Properties of the thioredoxin system in microaerophiles from the Streptococcus genus. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Properties of the thioredoxin system in microaerophiles from the Streptococcus genus
Date: 29 March 2013
Number of Pages: 116
Institution: Università degli Studi di Napoli Federico II
Department: Medicina Molecolare e Biotecnologie Mediche
Scuola di dottorato: Scienze biologiche
Dottorato: Biochimica e biologia cellulare e molecolare
Ciclo di dottorato: 25
Coordinatore del Corso di dottorato:
De Vendittis,
Date: 29 March 2013
Number of Pages: 116
Keywords: Thioredoxin system, Streptococcus mutans, Streptococcus thermophilus, Adaptatios to ROS control, Microaerophiles
Settori scientifico-disciplinari del MIUR: Area 05 - Scienze biologiche > BIO/10 - Biochimica
Aree tematiche (7° programma Quadro): SALUTE e TUTELA DEL CONSUMATORE > Biotecnologie, strumenti e tecnologie generiche per la salute umana
BIOTECNOLOGIE, PRODOTTI ALIMENTARI E AGRICOLTURA > Produzione sostenibile e gestione delle risorse biologiche della terra, della foresta e dell'ambiente acquatico
Date Deposited: 10 Apr 2013 15:47
Last Modified: 15 Jul 2014 13:36
DOI: 10.6092/UNINA/FEDOA/9229

Collection description

The Streptococcus genus includes the pathogenic species S. mutans, the main responsible of dental caries, and the safe microorganism S. thermophilus, used for the manufacture of dairy products. These facultative anaerobes control the levels of reactive oxygen species (ROS) and indeed, both S. mutans and S. thermophilus possess a cambialistic superoxide dismutase, the key enzyme for a preventive action against ROS. To evaluate the properties of a crucial mechanism for repairing ROS damages, the molecular and functional characterization of the thioredoxin system in these streptococci was investigated. The putative genes encoding its protein components in S. mutans and S. thermophilus were analysed and the corresponding recombinant proteins were purified. A single thioredoxin reductase was obtained from either S. mutans (SmTrxB) or S. thermophilus (StTrxB1), whereas two thioredoxins were prepared from either S. mutans (SmTrxA and SmTrxH1) or S. thermophilus (StTrxA1 and StTrxA2). Both SmTrxB and StTrxB1 reduced the synthetic substrate DTNB in the presence of NADPH, whereas only SmTrxA and StTrxA1 accelerated the insulin reduction in the presence of DTT. To reconstitute an in vitro streptococcal thioredoxin system, the combined activity of the thioredoxin components was tested through the insulin precipitation in the absence of DTT. The assay functions with a combination of SmTrxB or StTrxB1 with either SmTrxA or StTrxA1. These results suggest that the streptococcal members of the thioredoxin system display a direct functional interaction between them and that these protein components are interchangeable within the Streptococcus genus. In conclusion, our data prove the existence of a functioning thioredoxin system even in these microaerophiles.


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