At least two bacterioferritin genes are present in the genome of Pseudomonas aeruginosa, ftnA and bfrB. In previous work these genes have been cloned and the corresponding recombinant FtnA and BfrB proteins have been characterized biochemically and structurally. Bacterioferritin B has been shown to assemble into a 24-mer structure that binds 12 hemes and thus form a genuine bacterioferritin, whereas ferritin A has been shown to assemble into a 24-mer structure incapable of binding heme. These findings led to the idea that two ferritin-like structures, a ferritin (FtnA) and a bacterioferritin (BfrB) coexist in P. aeruginosa. While studying the effects of iron storage in P. aeruginosa cells, we noted that recombinant BfrB and FtnA have different electrophoretic mobility in native PAGE gels. Interestingly, the mobility of native bacterioferritin (isolated from cell lysates) is also distinct from that exhibited by FtnA or BfrB. Mass spectrometric analysis of the native bacterioferritin isolated from a native PAGE gel suggested that the protein is composed of two subunits FtnA, and BfrB. Purification and additional analysis corroborated the idea that native bacterioferritin from P. aeruginosa is assembled from two type of subunits. In this poster we will present the experimental details that enabled the purification of native bacterioferritin, as well as the analytical and structural approaches that led to its characterization.

Bacterioferritin from Pseudomonas aeruginosa PAO1 is assembled from two distinct subunits

2019 Fall National Meeting

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