Christopher Chang - Atomic Resolution Modeling of the Ferredoxin:[FeFe] Hydrogenase Complex from Chlamydomonas reinhardtii

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      Chang, C.H., PW King, ML Ghirardi & K Kim (2007) Biophys.   J. 93: 3034-45


      The [FeFe] hydrogenases HydA1 and HydA2 in the green alga   Chlamydomonas reinhardtii catalyze the final reaction in   a remarkable metabolic pathway allowing this photosynthetic   organism to produce H2 from water in the chloroplast.   A [2Fe-2S] ferredoxin is a critical branch point in electron flow   from Photosystem I toward a variety of metabolic fates, including   proton reduction by hydrogenases. To better understand the   binding determinants involved in ferredoxin:hydrogenase   interactions, we have modeled Chlamydomonas PetF1 and   HydA2 based on amino-acid sequence homology, and produced two   promising electron-transfer model complexes by computational   docking. To characterize these models, quantitative free energy   calculations at atomic resolution were carried out, and detailed   analysis of the interprotein interactions undertaken. The protein   complex model we propose for ferredoxin:HydA2 interaction is   energetically favored over the alternative candidate by 20   kcal/mol. This proposed model of the electron-transfer complex   between PetF1 and HydA2 permits a more detailed view of the   molecular events leading up to H2 evolution, and   suggests potential mutagenic strategies to modulate electron flow   to HydA2.

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