The gene ald, encoding aldehyde dehydrogenase, has been cloned from a genomic library of Escherichia coli K-12 constructed with plasmid pBR322 by complementing an aldehyde dehydrogenase-deficient mutant. The ald region was sequenced, and a single open reading frame of 479 codons specifying the subunit of the aldehyde dehydrogenase enzyme complex was identified. Determination of the N-terminal a...

Two distinct D-amino acid dehydrogenases, each showing absolute speci&ity for methylene blue or 2,6-dichloroindophenol, respectively, were isolated from Pseudomonas @orescens (ATCC 11299B). The methylene blue-specific ~-amino acid dehydrogenase was detectable only in extracts from D-tryptophan-grown cells and was purified about 40-fold. The 2,6-dichloroindophenol-specif?c ~-amino acid dehydroge...

Catabolism of the branched-chain amino acids is regulated in part at the step catalyzed by the branched-chain alpha-ketoacid dehydrogenase complex. Previous work suggests both short-term and long-term control mechanisms are involved in regulation of the kinase responsible for phosphorylation and inactivation of the branched-chain alpha-ketoacid dehydrogenase complex. Recent work of this laborat...

The presence of two kinds of l-amino acid dehydrogenase in resting spores of Bacillus subtilis was indicated. One of them was l-alanine dehydrogenase, which used only l-alanine as a substrate, and the other was nonspecific dehydrogenase, which used l-valine, l-isoleucine, l-leucine, and l-alanine (slightly) as substrates. Several properties of these dehydrogenases were compared.

The 2-oxo acid dehydrogenase complexes represent the classic examples of multienzyme complexes, a knowledge of whose structure and function has wide implications for our understanding of macromolecular assembly and organization and of protein structure and function. Each complex consists of multiple copies of three enzymes, termed El, E2 and E3. El is a 2-oxo acid dehydrogenase which has thiami...

Amino acids, leucine in particular, are known to inhibit autophagy, at least in part by their ability to stimulate MTOR-mediated signaling. Evidence is presented showing that glutamate dehydrogenase, the central enzyme in amino acid catabolism, contributes to leucine sensing in the regulation of autophagy. The data suggest a dual mechanism by which glutamate dehydrogenase activity modulates aut...

In order to grow in a simple salts medium in which ammonia provides the sole source of nitrogen, micro-organisms must possess some mechanism for the synthesis of amino acids from ammonia and intermediary metabolites. In many bacteria this requirement is fulfilled by the enzyme glutamate dehydrogenase (EC 1.4.1.4), which reductively aminates 2-oxoglutarate to glutamate. In other bacteria (partic...

Pseudomonas putida produces two lipoamide dehydrogenases, LPD-glc and LPD-val. LPD-val is specifically required as the lipoamide dehydrogenase of branched-chain keto acid dehydrogenase and LPD-glc fulfills all other requirements for lipoamide dehydrogenase. Both proteins are dimers with one FAD per subunit. LPD-glc has an absorption maximum at 455 nm, but LPD-val has a maximum at 460 nm. Compar...

Pseudomonads are the only organisms so far known to produce two lipoamide dehydrogenases (LPDs), LPD-Val and LPD-Glc. LPD-Val is the specific E3 component of branched-chain oxoacid dehydrogenase, and LPD-Glc is the E3 component of 2-ketoglutarate and possibly pyruvate dehydrogenases and the L-factor of the glycine oxidation system. Three mutants of Pseudomonas putida, JS348, JS350, and JS351, a...