Poster abstracts

Poster number 42 submitted by Pearson Maugeri

Driving protein conformational changes with light: Evidence for photoinduced structural rearrangement in a heterobimetallic Mn/Fe oxidase

Pearson T. Maugeri (Biophysics Graduate Program), Effie K. Miller (Ohio State Biochemistry Program), Zach R. Smith (Department of Chemistry and Biochemistry)

Abstract:
Metalloenzymes play a critical role in many of the life-giving reactions on the planet, such as photosynthesis and respiration. One group of metalloproteins, the ferritin-like superfamily, is involved in a diverse group of functions ranging from Fe and O2 storage and transport to C-H bond activation and deoxyribonucleotide biosynthesis. Recently, a new subgroup has been identified within the ferritin-like superfamily that can bind both Mn(II) and Fe(II) ions, counter to the well-established Irving-Williams series. This new group has been named the R2-like ligand-binding oxidases, or R2lox, due to its similarity in sequence and metal binding properties to the class 1c R2 subunit of the ribonucleotide reductases. R2lox possesses many characteristics that distinguish it from members of the canonical di-iron ferritin-like proteins, such as the ability to bind either Fe/Fe or Mn/Fe cofactors, the presence of an exogenous fatty acid lipid bound to the metal centers, and the capability to perform two-electron oxidation reactions, as evidenced by formation of a Tyr-Val crosslink upon oxygen activation. Recently, we have observed that R2lox undergoes a structural rearrangement in the active site upon photoirradiation. Using a variety of spectroscopic and photochemical methods, including a state-of-the-art resonance Raman system, a structure and mechanism for formation of this new state has been proposed. Future experiments relating this state to a possible biological function will be discussed.

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Keywords: metalloproteins, resonance Raman, photochemistry