Characterization of an Alcohol Dehydrogenase from the Cyanobacterium Synechocystis sp. Strain PCC 6803 That Responds to Environmental Stress Conditions via the Hik34-Rre1 Two-Component System

Abstract

The slr1192 (adhA) gene from Synechocystis sp. strain PCC 6803 encodes a member of the medium-chain alcohol dehydrogenase/reductase family. The gene product AdhA exhibits NADP-dependent alcohol dehydrogenase activity, acting on a broad variety of aromatic and aliphatic primary alcohols and aldehydes but not on secondary alcohols or ketones. It exhibits superior catalytic efficiency for aldehyde reduction compared to that for alcohol oxidation. The enzyme is a cytosolic protein present in photoautotrophically grown Synechocystis cells. The expression of AdhA is enhanced upon the exposure of cells to different environmental stresses, although it is not essential for survival even under such stress conditions. The induction of the expression of the adhA gene is dependent on the Hik34-Rre1 two-component system, as it is severely impaired in mutant strains lacking either the histidine kinase Hik34 or the response regulator Rre1. In vitro DNA-protein interaction analysis reveals that the response regulator Rre1 binds specifically to the promoter region of the adhA gene.

Biosynthesis of odd-chain fatty alcohols in Escherichia coli

“…4A). Slr1192 also had better improvement effect than the other 3 endogenous AHRs, which confirmed the conclusion that YjgB played the key role in biosynthesizing medium odd-chain fatty alcohols, since Slr1192 maintained 64% amino acid sequence similarity with YjgB (Akhtar et al, 2013;Vidal et al, 2009). Akhtar et al (2013) also proved YjgB was a fair AHR for the formation of C 8 -C 16 fatty alcohols.…”

Carboxylic acid reductase is a versatile enzyme for the conversion of fatty acids into fuels and chemical commodities

“…Based on a previous engineering approach (6), along with new insight on the enzymatic capability of CAR, we devised a unique metabolic pathway for the synthesis of fatty alcohols. This pathway comprised four gene products: Escherichia coli TesA for the liberation and metabolic overaccumulation of free fatty acids from the native acyl-ACP/ CoA metabolites, B. subtilis Sfp for activation of the CAR enzyme, M. marinum CAR for activation and subsequent reduction of the free fatty acid to the fatty aldehyde, and the previously characterized AHR from Synechocystis species PCC 6803, slr1192 (12), for further reduction of the fatty aldehyde to the fatty alcohol. Induction of the engineered pathway in E. coli under aerobic conditions in complex media resulted in the accumulation of both saturated and unsaturated fatty alcohols (C 12 -C 18 ) with a titer of ∼200 mg·L −1 of culture (Fig.…”

Fatty Aldehydes in Cyanobacteria Are a Metabolically Flexible Precursor for a Diversity of Biofuel Products

“…1). To test this, we co-expressed Aar with both a long-chain alcohol dehydrogenase from Synechocystis sp PCC 6803 (slr1192 [29]) and aDGAT. This resulted in wax ester production (Fig.…”