Iron uptake from siderophores

While much of our work is carried out in the lab under carefully controlled conditions, we also strive to investigate these phenomena in field populations.  For example, on our 2011 cruise to the Ross Sea, Antarctica, we demonstrated that Fe – enterobactin complexes are much more bioavailable to eukaryotic phytoplankton than previously thought.  This was somewhat unexpected given that these compounds release Fe very slowly- 

 – much too slow to support the high Fe demands of photosynthesis.  Also, biological Fe(III) reduction to Fe(II) is thought to be an important process in rendering some forms of Fe available, but these Fe-siderophore complexes are not  susceptible to biological reduction.  

Since then, our microarray experiments (in collaboration with Andy Allen at JCVI) with the marine diatom Phaeodactylum tricornutum revealed the intense up-regulation of a transcript encoding for a protein that may de-stabilize Fe enterobactin complexes.  Senior Honor’s college student Naeem Patel has obtained recent evidence that this protein may play a role in the diatom’s ability to access this siderophore bound Fe.  We are working on more definitive tests to evaluate the relationship between Fe-enterobactin availability and this protein.  These include reverse genetic experiments that allow us to probe the role of individual proteins through genetic modification of diatoms.