par Herman, Christophe 
;Lecat, Sandra;D'Ari, Richard;Bouloc, Philippe
Référence Molecular microbiology, 18, 2, page (247-255)
Publication Publié, 1995
;Lecat, Sandra;D'Ari, Richard;Bouloc, PhilippeRéférence Molecular microbiology, 18, 2, page (247-255)
Publication Publié, 1995
Article révisé par les pairs
| Résumé : | HfIB, also called FtsH, is an essential Escherichia coli protein involved in the proteolysis of the heat‐shock regulator σ32 and of the phage regulator λcll. The hfIB1(Ts) allele (formerly called ftsH1) conferring temperature‐sensitive growth at 42°C is suppressed by loss of the ferric‐uptake repressor Fur and by anaerobic growth. We show here that suppression requires TonB‐dependent Fe(III) transport in the hfIB1(Ts) fur mutant during aerobic growth at 42°C and Feo‐dependent Fe(II) transport during anaerobic growth at 42°C. Temperature‐resistant growth of hfIB1(Ts) strains is also observed at 42°C in the presence of a high concentration of Fe(II), Ni(II), Mn(II) or Co(II) salts, but not in the presence of Zn(II), Cd(II), Cu(II), Mg(II), Ca(II) or Cr(III) salts. However, neither Ni(II) nor a fur mutation permits growth in the complete absence of HfIB. The heat‐shock response, evaluated by an htpG::lacZ fusion, is overinduced in hfIB1(Ts) strains at 42°C because of stabilization of σ32. Growth in the presence of Ni(II) or in the absence of the Fur repressor abolishes this overinduction in the hfIB1(Ts) strain, and, in the hfIB1(Ts) fur mutant, σ32 is no longer stabilized at 42°C. These results reinforce the recent observation that HfIB is a metalloprotease active against σ32in vitro and suggest that it can associate functionally in vivo with Fe(II), Ni(II), Mn(II) and Co(II) ions. Copyright © 1995, Wiley Blackwell. All rights reserved |
