A. Ruepp et al., PROTEASOME FUNCTION IS DISPENSABLE UNDER NORMAL BUT NOT UNDER HEAT-SHOCK CONDITIONS IN THERMOPLASMA-ACIDOPHILUM, FEBS letters, 425(1), 1998, pp. 87-90
Hitherto the biology of proteolysis in prokaryotes, particularly in ar
chaea, is only poorly understood. We hale used the tri-peptide vinyl s
ulfone inhibitor carboxybenzyl-leucyl-leucyl-leucine vinyl sulfone (Z-
L-3 VS) to study the in vivo function of proteasomes in Thermoplasma a
cidophilum. Z-L-3 VS is a potent inhibitor of the Thermoplasma proteas
ome and is capable of modifying 75 to 80% of the proteasomal beta-subu
nits in cell cultures. Inhibition of proteasomes has only marginal eff
ects under normal growth conditions. Under heat shock conditions, howe
ver, the effects of proteasome inhibition are much more severe, to the
extent of complete cell growth arrest. These data suggest that other
proteolytic systems may exist that can compensate for the loss of prot
easome function in T. acidophilum. (C) 1998 Federation of European Bio
chemical Societies.