Prof. Dabney Dixon, Georgia State University

Heme Uptake in Pathogenic Bacteria

Biochemistry Division Seminar Series

Many bacteria get some or all of their heme from the environment. The pathways for this uptake, varying from organism to organism, are not yet well understood. We study two bacteria: Streptococcus pyogenes (strep throat, “flash eating disease”) and Corynebacterium diphtheriae (diphtheria). S. pyogenes obtains iron in part by heme uptake via the Sia (Hts) pathway. Heme is transferred from Shr to Shp to SiaA (part of an ABC transporter system). Shr has two heme-binding NEAT domains. Biophysical studies (including chemical denaturation, electrochemistry, NMR, MCD and Raman) of SiaA and both NEAT domains will be reported. Spectral signatures, sequence alignment and homology modeling for both domains have been used to assess the axial ligand possibilities. The uptake pathway in C. diphtheriae involves a pathway that has similarities to that in S. pyogenes but differs in many of the details. Characterization of the HmuT protein will be presented.

For more information contact Prof. Christoph Fahrni (404-385-1164).