In vitro methanol production from methyl coenzyme M using the Methanosarcina barkeri MtaABC protein complex.

Methanol:coenzyme M methyltransferase is an enzyme complex composed of three subunits, MtaA, MtaB, and MtaC, found in methanogenic archaea and is needed for their growth on methanol ultimately producing methane. MtaABC catalyzes the energetically favorable methyl transfer from methanol to coenzyme M to form methyl coenzyme M. Here we demonstrate that this important reaction for possible production of methanol from the anaerobic oxidation of methane can be reversed in vitro. To this effect, we have expressed and purified the Methanosarcina barkeri MtaABC enzyme, and developed an in vitro functional assay that demonstrates MtaABC can catalyze the energetically unfavorable (ΔG° = 27 kJ/mol) reverse reaction starting from methyl coenzyme M and generating methanol as a product. Demonstration of an in vitro ability of MtaABC to produce methanol may ultimately enable the anaerobic oxidation of methane to produce methanol and from methanol alternative fuel or fuel-precursor molecules. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1243-1249, 2017.

Trafficking and Oligomeric Regulation of Platelet-Activating Factor Acetylhydrolase Type II.

Platelet-activating factor acetylhydrolase type II, PAFAH-II, is an intracellular phospholipase A2 enzyme present in various tissues and cells. PAFAH-II hydrolyzes a known phospholipid-derived mediator, platelet-activating factor, as well as oxidatively fragmented phospholipids in cellular membranes. Although the crystal structure of PAFAH-II remains unsolved, homology modeling has provided insight into the components of its structure that are necessary for membrane localization and binding. PAFAH-II contains an N-terminal myristoyl tail as well as two hydrophobic helices that help to control the oligomeric state and the association of the enzyme to membranes. This chapter presents an overview of the experimental methods and results that have developed our current understanding of the trafficking of PAFAH-II to the cellular membranes, as well as the enzyme's natural oligomeric states related to its function.