AUTHOR=Rasmussen Casper Bøjer , Scavenius Carsten , Thøgersen Ida B. , Harwood Seandean Lykke , Larsen Øivind , Bjerga Gro Elin Kjaereng , Stougaard Peter , Enghild Jan J. , Thøgersen Mariane Schmidt 

TITLE=Characterization of a novel cold-adapted intracellular serine protease from the extremophile Planococcus halocryophilus Or1

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1121857

DOI=10.3389/fmicb.2023.1121857

ISSN=1664-302X

ABSTRACT=<p>The enzymes of microorganisms that live in cold environments must be able to function at ambient temperatures. Cold-adapted enzymes generally have less ordered structures that convey a higher catalytic rate, but at the cost of lower thermodynamic stability. In this study, we characterized P355, a novel intracellular subtilisin protease (ISP) derived from the genome of <italic>Planococcus halocryophilus</italic> Or1, which is a bacterium metabolically active down to −25°C. P355′s stability and activity at varying pH values, temperatures, and salt concentrations, as well as its temperature-dependent kinetics, were determined and compared to an uncharacterized thermophilic ISP (T0099) from <italic>Parageobacillus thermoglucosidasius</italic>, a previously characterized ISP (T0034) from <italic>Planococcus</italic> sp. AW02J18, and Subtilisin Carlsberg (SC). The results showed that P355 was the most heat-labile of these enzymes, closely followed by T0034. P355 and T0034 exhibited catalytic constants (<italic>k</italic><sub><italic>cat</italic></sub>) that were much higher than those of T0099 and SC. Thus, both P355 and T0034 demonstrate the characteristics of the stability-activity trade-off that has been widely observed in cold-adapted proteases.</p>