Abstract
The insect metalloproteinase inhibitor (IMPI) from the greater wax
moth, Galleria mellonella, represents the first and to date only
specific inhibitor of microbial metalloproteinases reported from
animals. Here, we report on the characterization including carbohydrate
analysis of two recombinant constructs encoded by impi cDNA either
upstream or downstream of the furin cleavage site identified. rIMPI-1,
corresponding to native IMPI purified from hemolymph, is encoded by the
N-terminal part of the impi sequence, whereas rIMPI-2 is encoded by its
C-terminal part. rIMPI-1 is glycosylated at N48 with GIcNAc2Man3,
showing fucosylation to different extents. Similarly, rIMPI-2 is
glycosylated at N149 with GIcNAc2Man3, but is fully fucosylated.
rIMPI-1 represents a promising template for the design of
second-generation antibiotics owing to its specific activity against
thermolysin-like metalloproteinases produced by human pathogenic
bacteria such as Vibrio vulnificus. In contrast, rIMPI-2 does not
inhibit bacterial metalloproteinases, but is moderately active against
recombinant human matrix metalloproteinases (MMPs). Both microbial
metalloproteinases and MMPs induce expression of the impi gene when
injected into G. mellonella larvae. These findings provide evidence
that the impi gene encodes two distinct inhibitors, one inhibiting
microbial metalloproteinases and contributing to innate immunity, the
other putatively mediating regulation of endogenous MMPs during
metamorphosis.
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