Detection of an intracellular protease inhibitor in archaea.
Proteolytic activity and a subtilisin inhibitor (NSI) were detected in Natrialba magadii cells. The proteolytic activity was due to two different proteases: a approximately 90-kDa metallo protease (NMP) produced during exponential growth and a 246-kDa serine protease (NSP) detected in the stationary phase. Both proteases were detected in the cytosolic fraction. NSI activity was maximal during early stages of growth and decreased in the stationary phase. NSI is a 35-kDa thermosensitive protein; it inhibits NSP activity but has no effect on NMP, and it was detected as a soluble or membrane-bound protein depending on the growth phase. Our results suggest that NSI may regulate NSP activity in vivo and that this protease may have a role in stationary phase cells. To our knowledge, this is the first report on the occurrence of protease inhibitors in Archaea.
Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Casilla de Correo 1245, (7600) Mar del Plata, Argentina.
María I
MI
Giménez
Jorge J
JJ
Sánchez
Rosana E
RE
De Castro
D002462:Cell Membrane / Q000378:metabolism; D003470:Culture Media; D003600:Cytosol / Q000378:metabolism; D006216:Halobacteriaceae / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D008666:Metalloendopeptidases / Q000378:metabolism; D011480:Protease Inhibitors / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism
D003470:Culture Media; D011480:Protease Inhibitors; D012697:Serine Endopeptidases; D008666:Metalloendopeptidases