Secretion of active beta-lactamase to the medium mediated by the Escherichia coli haemolysin transport pathway.

摘要: An in frame gene fusion containing the coding region for mature β-lactamase and 3′-end of hylA encoding haemolysin secretion signal, was constructed under control a lac promoter. The resulting 53 kDa hybrid protein specifically secreted to external medium presence translocator proteins, HlyB HlyD. specific activity portion (measured by hydrolysis penicillin G), approximately 1 U/μg protein, close that authentic, purified TEM-β-lactamase. This is an important example enzymatically active, via pathway. Previous studies have indicated directly into medium, bypassing periplasm, which normally targeted. study indicated, therefore, normal folding active β-lactamase, can occur, at least when fused HlyA C-terminus, without necessity entering periplasm. Despite 5 μg/ml levels there maximally only 50% detectable increase LD50 resistance ampicillin individual cell level. result suggests that, normally, requires high concentration enzyme killing targets, i.e. order achieve significant protection.