biostudies-literatureMeza ANIGMS NIH HHS10700-10710https://www.ebi.ac.uk/biostudies/studies/S-EPMC9681013biostudies-literatureUnknown12(17)Multi-enzyme biocatalytic cascades are emerging as practical routes for the synthesis of complex bioactive molecules. However, the relative sparsity of water-stable carbon electrophiles limits the synthetic complexity of molecules made from such cascades. Here, we develop a chemoenzymatic platform that leverages styrene oxide isomerase (SOI) to covert readily accessible aryl epoxides into α-aryl aldehydes through a Meinwald rearrangement. These unstable aldehyde intermediates are then intercepted with a C-C bond forming enzyme, ObiH, that catalyzes a transaldolase reaction with l-threonine to yield synthetically challenging β-hydroxy-α-amino acids. Co-expression of both enzymes in <i>E. coli</i> yields a whole cell biocatalyst capable of synthesizing a variety of stereopure non-standard amino acids (nsAA) and can be produced on <i>gram</i>-scale. We used isotopically labelled substrates to probe the mechanism of SOI, which we show catalyzes a concerted isomerization featuring a stereospecific 1,2-hydride shift. The viability of <i>in situ</i> generated α-aryl aldehydes was further established by intercepting them with a recently engineered decarboxylative aldolase to yield γ-hydroxy nsAAs. Together, these data establish a versatile method of producing α-aryl aldehydes in simple, whole cell conditions and show that these intermediates are useful synthons in C‒C bond forming cascades.ACS catalysisEfficient chemoenzymatic synthesis of α-aryl aldehydes as intermediates in C-C bond forming biocatalytic cascades.PMC9681013DP2 GM137417Grieger AMCampbell MEMcGill MJThein SAZmich AMeza AWilloughby PHBuller ARfalseEfficient chemoenzymatic synthesis of α-aryl aldehydes as intermediates in C-C bond forming biocatalytic cascades.Multi-enzyme biocatalytic cascades are emerging as practical routes for the synthesis of complex bioactive molecules. However, the relative sparsity of water-stable carbon electrophiles limits the synthetic complexity of molecules made from such cascades. Here, we develop a chemoenzymatic platform that leverages styrene oxide isomerase (SOI) to covert readily accessible aryl epoxides into α-aryl aldehydes through a Meinwald rearrangement. These unstable aldehyde intermediates are then intercepted with a C-C bond forming enzyme, ObiH, that catalyzes a transaldolase reaction with l-threonine to yield synthetically challenging β-hydroxy-α-amino acids. Co-expression of both enzymes in <i>E. coli</i> yields a whole cell biocatalyst capable of synthesizing a variety of stereopure non-standard amino acids (nsAA) and can be produced on <i>gram</i>-scale. We used isotopically labelled substrates to probe the mechanism of SOI, which we show catalyzes a concerted isomerization featuring a stereospecific 1,2-hydride shift. The viability of <i>in situ</i> generated α-aryl aldehydes was further established by intercepting them with a recently engineered decarboxylative aldolase to yield γ-hydroxy nsAAs. Together, these data establish a versatile method of producing α-aryl aldehydes in simple, whole cell conditions and show that these intermediates are useful synthons in C‒C bond forming cascades.2022-01-01T00:00:00Z2022 Sep2025-04-19T16:11:52.235Z2025-04-19T16:11:52.235ZS-EPMC96810133642047910.1021/acscatal.2c02369