Microbial Production of Natural and Unnatural Monolignols with Escherichia coli

Abstract

Phenylpropanoids and phenylpropanoid‐derived plant polyphenols find numerous applications in the food and pharmaceutical industries. In recent years, several microbial platform organisms have been engineered towards producing such compounds. However, for the most part, microbial (poly)phenol production is inspired by nature, so naturally occurring compounds have predominantly been produced to date. Here we have taken advantage of the promiscuity of the enzymes involved in phenylpropanoid synthesis and exploited the versatility of an engineered Escherichia coli strain harboring a synthetic monolignol pathway to convert supplemented natural and unnatural phenylpropenoic acids into their corresponding monolignols. The performed biotransformations showed that this strain is able to catalyze the stepwise reduction of chemically interesting unnatural phenylpropenoic acids such as 3,4,5‐trimethoxycinnamic acid, 5‐bromoferulic acid, 2‐nitroferulic acid, and a “bicyclic” p‐coumaric acid derivative, in addition to six naturally occurring phenylpropenoic acids.

Consolidated production of coniferol and other high-value aromatic alcohols directly from lignocellulosic biomass

“…Other routes to produce 3, and related phenylpropenoic acids, have been reported using different enzymatic routes to those reported here. 10,25,30,34 For example, a de novo biosynthetic route to 3 from tyrosine was developed using a 4-step enzyme cascade, consisting of a tyrosine ammonia lyase, 4-coumaroyl-CoA ligase, cinnamoyl-CoA reductase, and a cinnamyl alcohol dehydrogenase (TAL-4CL-CCR-CAD) affording 125 mg L −1 . 10 Two further studies used a similar 3-step enzyme cascade to produce 3 from 1 using a 4-coumaroyl-CoA ligase, a cinnamoyl-CoA reductase, and a cinnamyl alcohol dehydrogenase (4CL-CCR-CAD) yielding 327 mg L −1 30 and 108 mg L −1 34 of 3 from 1.…”

“…Overall, these results indicate that the whole cell biocatalyst reported here is useful for the production of biomass-derived aromatic alcohols and related molecules, and presents both more rapid and more complete conversion than other enzymatic strategies. 23,25,30,34,35 Consolidated biodegradation-biotransformation process…”

“…25 However, the reduction of ferulic acid to coniferol has not been explored using this proposed catalytic pathway, and indeed to our knowledge there are no reports of such a cascade using heterologous AKR enzymes. 23,[27][28][29][30] The generation of these chemicals from abundant biomass sources has many advantages including use of mild reaction conditions, compatibility with aqueous media, sourcing of catalysts from renewable feedstocks and chemo-, regio-and enantioselectivity. In this study we explored the use of both an in vitro enzymatic and whole-cell biocatalytic route to release ferulic acid from biomass sources and convert it directly into coniferol ( Fig.…”

Development of a Biosensor Platform for Phenolic Compounds Using a Transition Ligand Strategy

“…However, specific biosensors for the biotechnologically interesting aromatic compounds 4HCA, 4HBA, and 6MSA are highly desired. The same is true for 5BFA carrying bromine in ortho position as it offers the possibility to carry out palladium-catalyzed cross-coupling of the bromine group (Figure B) . The first biosensor for 4HCA and 4HBA have been constructed, but no sensors for 6MSA or 5BFA are available. − Hence, we aimed at expanding the detection repertoire of pSenCA, by semirationally engineering the ligand specificity of the wild-type HcaR regulator (HcaR WT ).…”

Assembly of Plant Enzymes in E. coli for the Production of the Valuable (−)-Podophyllotoxin Precursor (−)-Pluviatolide

“…Previous reports described the possibility to biosynthesize such lignan precursors in E. coli − or other microorganisms . Phenolic coupling of coniferyl alcohol leads to (±)-pinoresinol, which has been successfully produced in E.…”