Some Recent Literature

Dobritzsch, D., Konig, S., Schneider, G., & Lu, G.  High resolution crystal structure of pyruvate decarboxylase from Zymomonas mobilis – implications for substrate activation in pyruvate decarboxylases.  The Journal of Biological Chemistry.  1998

                The authors present a crystal structure of pyruvate decarboxylase (PDC) from the Zymomonas mobilis bacterium.  The presented PDC is one that has yet to be observed.  The pyruvate decarboxylase from the bacterium, ZmPDC, was determined by molecular displacement methods.  ZmPDC is a homotetramer.  Each monomer can be further divided into three domains: PYR, R, and PP.  Each domain has open alpha/beta topology.  At the dimer-dimer interface, they interpreted some residual electron density as citrate molecules.   The four citrates might contribute to the tetramer assembly by electrostatic interactions and hydrogen bonds to protein side chains.  A quaternary structure comparison of PDC from Z. mobilis and PDC from yeast shows structural differences that may be related to the differences in their kinetic behavior. 

Hokyoung S., Kyunghun M., Jungkwan, L. , Gyung, J., Jin-Cheol K., & Yin-Won, L.  Differential roles of pyruvate decarboxylase in aerial and embedded mycelia of the ascomycete Giberrela zeae.  FEMS Microbiology Letters. 2012

                The researchers knocked out the three PDC genes in the fungus Giberrela zeae.  In particular, they looked at PDC1 and its role in the pyruvate-acetaldehyde-acetate (PAA) pathway.  The PAA pathway is important for its role in lipid production.  When PDC1 was knocked out, lipid accumulation declined in the aerial, but not the embedded mycelia.  Therefore, PDC1 may function as a key enzyme in lipid production in the aerial mycelia, and it mat function differently in the embedded mycelia, where it is believed to be involved in energy generation by ethanol fermentation.  This is the first description of different physiological roles in the aerial and embedded mycelia for the same metabolic process in filamentous fungi.  PDC1 and the PPA pathway are important for lipid production in the aerial mycelia.  However, embedded mycelia seem to utilize them via ethanol fermentation for growth.

Kondo, T., Tezuka, H., Ishii, J., Matsuda, F., Ogino, C., and Kondo, A.  Genetic engineering to enhance the Ehrlich pathway and alter carbon flux for increased isobutanol production from glucose by Saccharomyces cerevisiae.  Journal of Biotechnology.  2012

Recently, much attention has been given to the production of higher alcohols by engineered bacteria.  Saccharomyces cerevisiae has much potential as a producer of alcohols due to its tolerance to low pH among other things.  Since the bacterium does not naturally produce alcohols significantly, the researchers sought to genetically engineer a way to increase production of the alcohol isobutanol.  Knocking out the PDC1 gene (see above), along with modification of culture conditions and enhancing the Ehrlich pathway, resulted in a 13-fold increase in isobutanol concentration.  The Ehrlich pathway was enhanced by overexpressing 2-keto acid decarboxylase, alcohol dehydrogenase, and IIv2.