Patent classifications
C12Y101/02007
MICROORGANISMS AND METHODS FOR ENHANCING THE AVAILABILITY OF REDUCING EQUIVALENTS IN THE PRESENCE OF METHANOL, AND FOR PRODUCING 1,4-BUTANEDIOL RELATED THERETO
Provided herein is a non-naturally occurring microbial organism having a methanol metabolic pathway that can enhance the availability of reducing equivalents in the presence of methanol. Such reducing equivalents can be used to increase the product yield of organic compounds produced by the microbial organism, such as 1,4-butanediol (BDO). Also provided herein are methods for using such an organism to produce BDO.
Methanol dehydrogenase fusion proteins
Described herein are fusion proteins including methanol dehydrogenase (MeDH) and at least one other polypeptide such as 3-hexulose-6-phosphate dehydrogenase (HPS) or 6-phospho-3-hexuloisomerase (PHI), such as DHAS synthase or fructose-6-Phosphate aldolase or such as DHA synthase or DHA kinase. In a localized manner, the fusion protein can promote the conversion of methanol to formaldehyde and then to a ketose phosphate such as hexulose 6-phosphate or then to DHA and G3P. When expressed in cells, the fusion proteins can promote methanol uptake and rapid conversion to the ketose phosphate or to the DHA and D3P, which in turn can be used in a pathway for the production of a desired bioproduct. Beneficially, the rapid conversion to the ketose phosphate or to the DHA and G3P can avoid the undesirable accumulation of formaldehyde in the cell. Also described are engineered cells expressing the fusion protein, optionally include one or more additional metabolic pathway transgene(s), methanol metabolic pathway genes, target product pathway genes, cell culture compositions including the cells, methods for promoting production of the target product or intermediate thereof from the cells, compositions including the target product or intermediate, and products made from the target product or intermediate.
METALLOENZYMES AND CATALYTIC OXIDATION OF METHANOL
Discovery of the first rare earth-dependent enzyme in methylotrophic M. extorquens AM1 prompted research toward understanding the unique chemistry at play in these systems. This enzyme, an alcohol dehydrogenase (ADH), features a La.sup.3+ ion closely associated with redox-active coenzyme pyrroloquinoline quinone (PQQ). AM1 also produces a periplasmic PQQ-binding protein characterized by a Lys residue hydrogen-bonded to PQQ. Accordingly, we prepared K.sub.115A-, and K.sub.115D-PqqT variants to assess the relevance of this site toward metal binding. Isothermal titration calorimetry experiments, and titrations monitored by UV-vis absorption and emission spectroscopies support that K.sub.115D-PqqT binds tightly (K.sub.d=0.60.2 M) to La.sup.3+ in the presence of bound PQQ and produces spectral signatures consistent with those of ADH enzymes. Addition of benzyl alcohol to La.sup.3+-bound PQQK.sub.115D-PqqT produces spectroscopic changes associated with PQQ reduction, and chemical trapping experiments reveal the production of benzaldehyde, supporting ADH activity.