Related Experiment Videos
Degradation of extracellular matrix proteins by hemorrhagic metalloproteinases
E N Baramova1, J D Shannon, J B Bjarnason
1Department of Microbiology, University of Virginia Health Sciences Center, Charlottesville 22908.
Insights
Four hemorrhagic metalloproteinases from Crotalus atrox venom degrade extracellular matrix proteins like fibronectin and collagen. These snake venom enzymes show distinct specificities, contributing to hemorrhage by damaging basement membranes.
Area of Science:
- Biochemistry
- Toxicology
- Molecular Biology
Background:
- Snake venom contains metalloproteinases that cause hemorrhage.
- Extracellular matrix (ECM) proteins are crucial for maintaining tissue integrity.
- Understanding the substrate specificity of venom metalloproteinases is key to understanding their pathological effects.
Purpose of the Study:
- To investigate the proteolytic activity of four hemorrhagic metalloproteinases (Ht-a, Ht-c, Ht-d, Ht-e) from Crotalus atrox venom.
- To determine the specific extracellular matrix (ECM) proteins degraded by these metalloproteinases.
- To compare the substrate specificities of these venom metalloproteinases.
Main Methods:
- Isolated four hemorrhagic metalloproteinases (Ht-a, c, d, e) from Crotalus atrox venom.
- Assessed proteolytic activity against various purified ECM proteins, including fibronectin, laminin, type IV collagen, nidogen, and different gelatins.
- Analyzed and compared the resulting digestion patterns for each proteinase and substrate.
Main Results:
- All four metalloproteinases effectively cleaved fibronectin, laminin, type IV collagen, nidogen, and gelatins.
- None of the enzymes degraded interstitial collagens (types I, III, V).
- Ht-c and Ht-d exhibited identical digestion patterns, while Ht-a and Ht-e showed unique and partially shared patterns, indicating differing specificities.
Conclusions:
- Crotalus atrox hemorrhagic metalloproteinases efficiently degrade key ECM components, particularly those in basement membranes.
- These enzymes display both common and distinct substrate specificities, contributing to their hemorrhagic activity.
- The degradation of ECM proteins by these toxins likely leads to the loss of capillary integrity and subsequent hemorrhage.
Abstract:
The proteolytic activity of four hemorrhagic metalloproteinases (Ht-a, c, d, and e) isolated from the venom of the Western diamondback rattlesnake (Crotalus atrox) was investigated using isolated extracellular matrix (ECM) proteins. We determined that all of the proteinases are capable of cleaving fibronectin, laminin, type IV collagen, nidogen (entactin), and gelatins. However, none of the proteinases were proteolytic against the interstitial collagen types I and III or type V collagen. With all of the substrates listed above Ht-c and Ht-d produced identical digestion patterns, as would be expected for these isoenzymes. With fibronectin, Ht-a produces a different ratio of products from Ht-c and Ht-d, while Ht-e produces a unique pattern of digestion. Ht-e and Ht-a produced nonidentical patterns with the laminin/nidogen preparation although some similarity was shared between them as well as with the Ht-c/d digestion pattern. Similar results were also observed for these proteinases with nidogen 150 as the substrate. The type IV collagen digestion patterns by Ht-e and Ht-a were similar to the pattern observed with Ht-c/d but differed by two bands. The digestion patterns of the three gelatins produced by the proteinases show differences between Ht-c and Ht-d when compared to Ht-e and Ht-a. This investigation clearly shows that several of the ECM proteins are efficiently digested by these toxins. The proteinases have some digestion sites in common but show differing specificities. In addition, the range of ECM proteins digested by these hemorrhagic proteinases is nearly identical to that demonstrated by the ECM proteinase stromelysin (MMP-3). From these data, and the knowledge of the roles these ECM proteins have in maintaining basement membrane structural/functional integrity, one can envision that the degradation of these ECM proteins could readily lead to loss of capillary integrity resulting in hemorrhage occurring at those sites.