The Iron regulated Surface Determinant system (ISD)

The crystal structure of Staphylococcus aureus IsdG

In order for bacterial pathogens to utilize heme as an iron source, they must have a method of degrading heme to release the internalized iron atom. We have identified a novel heme degrading enzyme family that is conserved across multiple Gram positive pathogens. We have named this family the IsdG family of heme monoxygenases, and one area of research in our laboratory combines biochemistry, structural biology, and pathogenesis experiments to characterize this new class of bacterial enzymes.

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Red blood cell lysis caused by bacterial hemolysins

Iron is an essential nutrient to virtually all living organisms. Bacterial pathogens are no exception, as they require iron for numerous cellular processes. Vertebrate hosts have exploited this fact by preventing bacterial iron acquisition through the production of numerous iron binding proteins. The most prominent iron binding protein inside humans is the heme containing protein hemoglobin. Hemoglobin is the oxygen carrying molecule of red blood cells, and as such hemoglobin is predicted to be a rich iron source to bacterial pathogens of the blood such as Staphylococcus aureus and Bacillus anthracis. A well known attribute of S. aureus is its ability to lyse red blood cells in vitro through the production of staphylococcal hemolysins. We believe the red blood cell lysis is a pathogenic strategy employed by S. aureus to increase the local amount of available iron and we are testing this theory using a variety of experimental techniques. ⇒