TY  - JOUR
AU  - Bolton, Rachel
AU  - Machelett, Moritz M.
AU  - Stubbs, Jack
AU  - Axford, Danny
AU  - Caramello, Nicolas
AU  - Catapano, Lucrezia
AU  - Malý, Martin
AU  - Rodrigues, Matthew J.
AU  - Cordery, Charlotte
AU  - Tizzard, Graham J.
AU  - MacMillan, Fraser
AU  - Engilberge, Sylvain
AU  - von Stetten, David
AU  - Tosha, Takehiko
AU  - Sugimoto, Hiroshi
AU  - Worrall, Jonathan A. R.
AU  - Webb, Jeremy S.
AU  - Zubkov, Mike
AU  - Coles, Simon
AU  - Mathieu, Eric
AU  - Steiner, Roberto A.
AU  - Murshudov, Garib
AU  - Schrader, Tobias E.
AU  - Orville, Allen M.
AU  - Royant, Antoine
AU  - Evans, Gwyndaf
AU  - Hough, Michael A.
AU  - Owen, Robin L.
AU  - Tews, Ivo
TI  - A redox switch allows binding of Fe(II) and Fe(III) ions in the cyanobacterial iron-binding protein FutA from Prochlorococcus
JO  - Proceedings of the National Academy of Sciences of the United States of America
VL  - 121
IS  - 12
SN  - 0027-8424
CY  - Washington, DC
PB  - National Acad. of Sciences
M1  - FZJ-2024-02483
SP  - e2308478121
PY  - 2024
AB  - The marine cyanobacterium Prochlorococcus is a main contributor to global photosynthesis, whilst being limited by iron availability. Cyanobacterial genomes generally encode two different types of FutA iron-binding proteins: periplasmic FutA2 ABC transporter subunits bind Fe(III), while cytosolic FutA1 binds Fe(II). Owing to their small size and their economized genome Prochlorococcus ecotypes typically possess a single futA gene. How the encoded FutA protein might bind different Fe oxidation states was previously unknown. Here, we use structural biology techniques at room temperature to probe the dynamic behavior of FutA. Neutron diffraction confirmed four negatively charged tyrosinates, that together with a neutral water molecule coordinate iron in trigonal bipyramidal geometry. Positioning of the positively charged Arg103 side chain in the second coordination shell yields an overall charge-neutral Fe(III) binding state in structures determined by neutron diffraction and serial femtosecond crystallography. Conventional rotation X-ray crystallography using a home source revealed X-ray-induced photoreduction of the iron center with observation of the Fe(II) binding state; here, an additional positioning of the Arg203 side chain in the second coordination shell maintained an overall charge neutral Fe(II) binding site. Dose series using serial synchrotron crystallography and an XFEL X-ray pump–probe approach capture the transition between Fe(III) and Fe(II) states, revealing how Arg203 operates as a switch to accommodate the different iron oxidation states. This switching ability of the Prochlorococcus FutA protein may reflect ecological adaptation by genome streamlining and loss of specialized FutA proteins.
LB  - PUB:(DE-HGF)16
C6  - 38489389
UR  - <Go to ISI:>//WOS:001206418700003
DO  - DOI:10.1073/pnas.2308478121
UR  - https://juser.fz-juelich.de/record/1024817
ER  -