An extracellular metalloprotease (vEP) secreted by Vibrio vulnificus ATCC29307 is a 45-kDa proteolytic enzyme that has prothrombin activation and fibrinolytic activities during bacterial infection. The action of vEP could result in clotting that could serve to protect the bacteria from the host defense machinery. Very recently, we showed that the C-terminal propeptide (C-ter100), which is unique to vEP, is involved in regulation of vEP activity. To understand the structural basis of this function of vEP C-ten l 00, we have determined the solution structure and backbone dynamics using multidimensional nuclear magnetic resonance spectroscopy. The solution structure shows that vEP C-ten l 00 is composed of eight anti-parallel beta-strands with a unique fold that has a compact beta-barrel formation which stabilized by hydrophobic and hydrogen bonding networks. Protein dynamics shows that the overall structure, including loops, is very rigid and stabilized. By structural database analysis, we found that vEP C-ten 100 shares its topology with that of the collagen-binding domain of collagenase, despite low sequence homology between the two domains. Fluorescence assay reveals that vEP C-ten l 00 interacts strongly with iron (Fe3+). These findings suggest that vEP protease might recruit substrate molecules, such as collagen, by binding at C-ten l 00 and that vEP participates in iron uptake from iron-withholding proteins of the host cell during infection. (C) 2012 Elsevier Inc. All rights reserved.