A 4-hydroxybenzoate 3-hydroxylase mutant enables 4-amino-3-hydroxybenzoic acid production from glucose in Corynebacterium glutamicum.

Background: Microbial production of aromatic chemicals is an attractive method for obtaining high-performance materials from biomass resources. A non-proteinogenic amino acid, 4-amino-3-hydroxybenzoic acid (4,3-AHBA), is expected to be a precursor of highly functional polybenzoxazole polymers; however, methods for its microbial production have not been reported. In this study, we attempted to produce 4,3-AHBA from glucose by introducing 3-hydroxylation of 4-aminobenzoic acid (4-ABA) into the metabolic pathway of an industrially relevant bacterium, Corynebacterium glutamicum.

Efficient monoacylglycerol synthesis by carboxylesterase EstGtA2 from Geobacillus thermodenitrificans in a solvent-free two-phase system.

The present study investigated high-yield monoacylglycerol (MAG) synthesis by bacterial lipolytic enzymes in a solvent-free two-phase system. Esterification by monoacylglycerol lipase from Bacillus sp. H-257 (H257) required a high glycerol/fatty acid molar ratio for efficient MAG synthesis.

Variants of the industrially relevant protease KP-43 with suppressed activity under alkaline conditions developed using expanded genetic codes.

In the present study, we attempted to control the pH profile of the catalytic activity of the industrially relevant alkaline protease KP-43, by incorporating 3-nitro-l-tyrosine and 3-chloro-l-tyrosine at and near the catalytic site. Thirty KP-43 variants containing these non-natural amino acids at the specific positions were synthesized in host cells with expanded genetic codes. The variant with 3-nitrotyrosine at position 205, near the substrate binding site, retained its catalytic activity at the neutral pH and showed a 60% activity reduction at pH 10.

Specific expression and function of the A-type cytochrome c oxidase under starvation conditions in Pseudomonas aeruginosa.

Pseudomonas aeruginosa has one A-type (caa3) and multiple C-type (cbb3) cytochrome c oxidases as well as two quinol oxidases for aerobic respiration. The caa3 oxidase is highly efficient in creating a proton gradient across the cell membrane, but it is not expressed under normal growth conditions and its physiological role has not been investigated. In the present study, a mutant strain deficient in the coxBA-PA0107-coxC genes encoding caa3 exhibited normal growth under any test conditions, but it had low relative fitness under carbon starvation conditions, indicating that the expression of caa3 is advantageous under starvation conditions.

Expression of multiple cytochrome oxidase isoforms by combinations of multiple isosubunits in .

The ubiquitous opportunistic human pathogen has five terminal oxidases for aerobic respiration and uses them under different growth conditions. Two of them are -type cytochrome oxidases encoded by the gene clusters and , which are the main terminal oxidases under high- and low-oxygen conditions, respectively. also has two orphan gene clusters, and , encoding the core catalytic CcoN isosubunits, but the roles of these genes have not been clarified.

Enzymatic characterization and in vivo function of five terminal oxidases in Pseudomonas aeruginosa.

The ubiquitous opportunistic pathogen Pseudomonas aeruginosa has five aerobic terminal oxidases: bo(3)-type quinol oxidase (Cyo), cyanide-insensitive oxidase (CIO), aa3-type cytochrome c oxidase (aa3), and two cbb(3)-type cytochrome c oxidases (cbb(3)-1and cbb(3)-2). These terminal oxidases are differentially regulated under various growth conditions and are thought to contribute to the survival of this microorganism in a wide variety of environmental niches. Here, we constructed multiple mutant strains of P.