The rate of folding dictates substrate secretion by the Escherichia coli hemolysin type 1 secretion system. - Archive ouverte HAL
Article Dans Une Revue Journal of Biological Chemistry Année : 2010

The rate of folding dictates substrate secretion by the Escherichia coli hemolysin type 1 secretion system.

Patrick J Bakkes
  • Fonction : Auteur
Stefan Jenewein
  • Fonction : Auteur
Sander H J Smits
  • Fonction : Auteur
Lutz Schmitt
  • Fonction : Auteur

Résumé

Secretion of the Escherichia coli toxin hemolysin A (HlyA) is catalyzed by the membrane protein complex HlyB-HlyD-TolC and requires a secretion sequence located within the last 60 amino acids of HlyA. The Hly translocator complex exports a variety of passenger proteins when fused N-terminal to this secretion sequence. However, not all fusions are secreted efficiently. Here, we demonstrate that the maltose binding protein (MalE) lacking its natural export signal and fused to the HlyA secretion signal is poorly secreted by the Hly system. We anticipated that folding kinetics might be limiting secretion, and we therefore introduced the "folding" mutation Y283D. Indeed this mutant fusion protein was secreted at a much higher level. This level was further enhanced by the introduction of a second MalE folding mutation (V8G or A276G). Secretion did not require the molecular chaperone SecB. Folding analysis revealed that all mutations reduced the refolding rate of the substrate, whereas the unfolding rate was unaffected. Thus, the efficiency of secretion by the Hly system is dictated by the folding rate of the substrate. Moreover, we demonstrate that fusion proteins defective in export can be engineered for secretion while still retaining function.

Dates et versions

hal-00603812 , version 1 (27-06-2011)

Identifiants

Citer

Patrick J Bakkes, Stefan Jenewein, Sander H J Smits, I Barry Holland, Lutz Schmitt. The rate of folding dictates substrate secretion by the Escherichia coli hemolysin type 1 secretion system.. Journal of Biological Chemistry, 2010, 285 (52), pp.40573-80. ⟨10.1074/jbc.M110.173658⟩. ⟨hal-00603812⟩
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