Identification of the Dinuclear Metallo-Cofactor and Elucidation of the Reaction Mechanism of the Aldehyde Decarbonylase from the Alkane-producing Cyanobacterium Nostoc Punctiforme

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This award in the molecular biosciences program supports work at the Pennsylvania State University to study the enzyme aldehyde decarbonylase (AD) from the alkane-producing cyanobacterium Nostoc punctiforme (Np). The reaction catalyzed by Np AD is the second of the two reactions in the biosynthesis of alkanes by cyanobacteria. Thus, research supported by this project aims at elucidating the detailed chemical steps of the key alkane-producing step in cyanobacteria. Because cyanobacteria are environmentally versatile, rapidly growing, genetically alterable, and (most importantly) photosynthetic, they are being actively pursued as a vehicle for development of renewable energy. These studies include the identification of the dinuclear metallocofactor required for activity of Np AD and determination of the reaction mechanism of Np AD by a combination of biochemical and biophysical approaches. The utilization of fatty acids suggests that the soluble Np AD has devised a novel strategy to obtain this water insoluble substrate. The mechanism of substrate acquisition by Np AD will also be evaluated to differentiate between a channeling mechanism and membrane targeting. This project uses a versatile set of experimental strategies to evaluate the biosynthesis of alkanes. The results from these proposed studies will provide valuable information on new chemical properties of an enzyme metal center. The broader impacts of this work are two-fold. First, the research area at the interface of biological and inorganic chemistry is very interdisciplinary and offers students and postdoctoral scholars to be trained in a wide variety of methods. A workshop will be offered by bioinorganic chemists from Penn State and other institutions to approximately 80 students and postdoctoral scholars as a unique training opportunity in many of the methods used in this research field. Second, the research is relevant for the development of renewable energy, because the use of cyanobacteria for alkane production is a promising strategy for biofuel production. This process is particularly environmentally friendly, because the process is (i) carbon neutral (all carbon found in the alkane product derives from carbon dioxide fixed by the cyanobacteria) and (ii) driven by solar energy (due to the photosynthetic nature of cyanobacteria). This project will aid in the rational design of genetically engineered cyanobacteria for enhanced biofuel production.