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Evidence for non-siderophore-mediated acquisition of transferrin-bound iron by Pasteurella multocida
J A Ogunnariwo1, J Alcantara, A B Schryvers
1Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
Abstract:
Two clinical isolates of Pasteurella multocida associated with bovine pneumonia were examined for iron acquisition. Both isolates were capable of obtaining iron for growth from bovine but not from human, avian, equine or porcine transferrin. This correlated with specific binding of bovine transferrin by iron-limited cells or isolated membranes. No siderophore was detected in the strains by a general screening assay. In response to iron-limited conditions, a number of high molecular mass iron-regulated outer membrane proteins were produced including an 82 kDa receptor protein which was affinity isolated with biotinylated transferrin. In contrast, avian strains of P. multocida could not use transferrin-bound for growth and did not express either transferrin binding activity or the 82 kDa receptor protein.
Insights
Bovine pneumonia Pasteurella multocida strains acquire iron from bovine transferrin, unlike avian strains. This involves specific iron-regulated outer membrane proteins, including an 82 kDa receptor.
Area of Science:
- Microbiology
- Veterinary Medicine
- Molecular Biology
Background:
- Pasteurella multocida is a significant pathogen causing bovine pneumonia.
- Iron acquisition is crucial for bacterial growth and virulence.
- Transferrin is a primary iron-binding protein in mammalian serum.
Purpose of the Study:
- To investigate the iron acquisition mechanisms of Pasteurella multocida clinical isolates from bovine pneumonia.
- To determine the role of transferrin and specific outer membrane proteins in iron uptake.
- To compare iron acquisition strategies between bovine and avian strains of P. multocida.
Main Methods:
- Growth assays using various sources of iron-bound transferrin.
- Iron-limited culture conditions to induce iron-regulated protein expression.
- Outer membrane protein analysis and affinity isolation of transferrin-binding proteins using biotinylated transferrin.
Main Results:
- Bovine P. multocida isolates specifically utilized bovine transferrin for growth.
- Iron-limited bovine isolates expressed iron-regulated outer membrane proteins, including an 82 kDa transferrin receptor.
- Avian P. multocida strains showed no ability to utilize transferrin-bound iron or express the 82 kDa receptor.
Conclusions:
- Bovine clinical isolates of P. multocida possess a specific mechanism for acquiring iron from bovine transferrin.
- An 82 kDa outer membrane protein functions as a transferrin receptor in bovine strains, facilitating iron uptake.
- This specific iron acquisition system is absent in avian P. multocida strains, highlighting host-specific adaptations.