Int. J. Mol. Sci. 2014, 15(2), 3204-3219; doi:10.3390/ijms15023204
Article

A New Pepstatin-Insensitive Thermopsin-Like Protease Overproduced in Peptide-Rich Cultures of Sulfolobus solfataricus

Received: 5 December 2013; in revised form: 26 January 2014 / Accepted: 11 February 2014 / Published: 21 February 2014
(This article belongs to the Special Issue Thermophilic DNases, RNases and Proteases)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: In this study, we gain insight into the extracellular proteolytic system of Sulfolobus solfataricus grown on proteinaceous substrates, providing further evidence that acidic proteases were specifically produced in response to peptide-rich media. The main proteolytic component was the previously isolated SsMTP (Sulfolobus solfataricus multi-domain thermopsin-like protease), while the less abundant (named SsMTP-1) one was purified, characterized and identified as the sso1175 gene-product. The protein revealed a multi-domain organization shared with the cognate SsMTP with a catalytic domain followed by several tandemly-repeated motifs. Moreover, both enzymes were found spread across the Crenarchaeota phylum and belonging to the thermopsin family, although segregated into diverse phylogenetic clusters. SsMTP-1 showed a 75-kDa molecular mass and was stable in the temperature range 50–90 °C, with optimal activity at 70 °C and pH 2.0. Serine, metallo and aspartic protease inhibitors did not affect the enzyme activity, designating SsMTP-1 as a new member of the pepstatin-insensitive aspartic protease family. The peptide-bond-specificity of SsMTP-1 in the cleavage of the oxidized insulin B chain was uncommon amongst thermopsins, suggesting that it could play a distinct, but cooperative role in the protein degradation machinery. Interestingly, predictions of the transmembrane protein topology of SsMTP and SsMTP-1 strongly suggest a possible contribution in signal-transduction pathways.
Keywords: Sulfolobus solfataricus; thermopsin; thermophilic enzyme; signal-transduction pathways
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MDPI and ACS Style

Gogliettino, M.; Riccio, A.; Cocca, E.; Rossi, M.; Palmieri, G.; Balestrieri, M. A New Pepstatin-Insensitive Thermopsin-Like Protease Overproduced in Peptide-Rich Cultures of Sulfolobus solfataricus. Int. J. Mol. Sci. 2014, 15, 3204-3219.

AMA Style

Gogliettino M, Riccio A, Cocca E, Rossi M, Palmieri G, Balestrieri M. A New Pepstatin-Insensitive Thermopsin-Like Protease Overproduced in Peptide-Rich Cultures of Sulfolobus solfataricus. International Journal of Molecular Sciences. 2014; 15(2):3204-3219.

Chicago/Turabian Style

Gogliettino, Marta; Riccio, Alessia; Cocca, Ennio; Rossi, Mosè; Palmieri, Gianna; Balestrieri, Marco. 2014. "A New Pepstatin-Insensitive Thermopsin-Like Protease Overproduced in Peptide-Rich Cultures of Sulfolobus solfataricus." Int. J. Mol. Sci. 15, no. 2: 3204-3219.

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