The invention provides a non-naturally occurring microbial biocatalyst including a microbial organism having a 4-hydroxybutanoic acid (4-HB) biosynthetic pathway having at least one exogenous nucleic acid encoding 4-hydroxybutanoate dehydrogenase, succinyl-CoA synthetase, CoA-dependent succinic semialdehyde dehydrogenase, or -ketoglutarate decarboxylase, wherein the exogenous nucleic acid is expressed in sufficient amounts to produce monomeric 4-hydroxybutanoic acid (4-HB). Also provided is a non-naturally occurring microbial biocatalyst including a microbial organism having 4-hydroxybutanoic acid (4-HB) and 1,4-butanediol (BDO) biosynthetic pathways, the pathways include at least one exogenous nucleic acid encoding 4-hydroxybutanoate dehydrogenase, succinyl-CoA synthetase, CoA-dependent succinic semialdehyde dehydrogenase, 4-hydroxybutyrate:CoA transferase, 4-butyrate kinase, phosphotransbutyrylase, -ketoglutarate decarboxylase, aldehyde dehydrogenase, alcohol dehydrogenase or an aldehyde/alcohol dehydrogenase, wherein the exogenous nucleic acid is expressed in sufficient amounts to produce 1,4-butanediol (BDO). Additionally provided is a method for the production of 4-HB. The method includes culturing a non-naturally occurring microbial organism having a 4-hydroxybutanoic acid (4-HB) biosynthetic pathway including at least one exogenous nucleic acid encoding 4-hydroxybutanoate dehydrogenase, succinyl-CoA synthetase, CoA-dependent succinic semialdehyde dehydrogenase or -ketoglutarate decarboxylase under substantially anaerobic conditions for a sufficient period of time to produce monomeric 4-hydroxybutanoic acid (4-HB). Further provided is a method for the production of BDO. The method includes culturing a non-naturally occurring microbial biocatalyst, comprising a microbial organism having 4-hydroxybutanoic acid (4-HB) and 1,4-butanediol (BDO) biosynthetic pathways, the pathways including at least one exogenous nucleic acid encoding 4-hydroxybutanoate dehydrogenase, succinyl-CoA synthetase, CoA-dependent succinic semialdehyde dehydrogenase, 4-hydroxybutyrate:CoA transferase, 4-hydroxybutyrate kinase, phosphotranshydroxybutyrylase, -ketoglutarate decarboxylase, aldehyde dehydrogenase, alcohol dehydrogenase or an aldehyde/alcohol dehydrogenase for a sufficient period of time to produce 1,4-butanediol (BDO). The 4-HB and/or BDO products can be secreted into the culture medium.

The invention relates generally to a method of treatment for a human genetic disease, such as diseases characterized by unbalanced nucleotide pools, e.g., mitochondrial DNA depletion syndromes, and more specifically, thymidine kinase 2 (TK2) deficiency, using gene therapy. The gene therapy may involve administration of one or more constructs, such as a viral vector, containing a nucleic acid encoding a functional protein. The functional protein may correspond to a nuclear gene. For treatment of TK2 deficiency, the gene therapy may involve administration of one or more constructs, such as a viral vector, containing a nucleic acid encoding a functional TK2 enzyme. The treatment may also involve the administration of pharmacological therapy in conjunction with the gene therapy. The treatment protocols of the disclosure, such as those involving gene therapy alone or in combination with pharmacological therapy, can be used to treat, prevent, and/or cure various other disorders of unbalanced nucleoside pools, especially those found in mitochondrial DNA depletion syndrome.

Disclosed herein are methods for producing tulipalin A (-methylene--butyrolactone), recombinant cells or organisms for producing tulipalin A, enzymes needed for producing tulipalin A, and nucleic acids for expression of those enzymes.