The Magnetosome Membrane Protein Mms6 Produces MR Contrast In Vitro

Xiaoyong Zhang¹, Brenda Robledo¹, Steven Harris¹, Xiaoping Hu¹

Magnetotactic bacteria produce organelles called magnetosomes that contain iron oxide crystals. Mms6 is a protein thought to initiate magnetite crystal nucleation within the magnetosome. Because of this function, we hypothesized that mms6 expressed in mammalian cells would function as a reporter gene by effecting iron oxide crystal formation that can be measured with MRI. We isolated a clonal cell line expressing mms6 and incubated the cells in iron supplemented growth media. We found a statistically significant increase in transverse relaxivity, R2, with increasing iron concentration for the cells expressing mms6 suggesting it may function as an MR reporter gene.