title: In vivo instability of chorismate causes substrate loss during fermentative production of aromatics.
abstract: Metabolic engineering of microbial strains to produce aromatic compounds deriving from the shikimate pathway is of great interest to the chemical industry as a more sustainable alternative for feedstock production. Chorismate is a significant intermediate in the shikimate pathway. In this study, the formation of phenylalanine and phenylpyruvate as by-products in strains engineered downstream of the chorismate node for increased aromatic production was explored in yeast fermentations. Tracer experiments showed that these compounds are synthesized de novo during fermentation, under conditions in which their synthesis was genetically blocked. Chorismate stability evaluation, as well as deletion mutation analysis throughout the phenylalanine biosynthesis pathway, suggested that this synthesis was a result of intracellular, non-enzymatic rearrangement of chorismate to phenylpyruvate via prephenate, which was followed by enzymatic transamination of phenylpyruvate to form phenylalanine. These results not only aid in the development of strain-engineering strategies to avoid the accumulation of by-products during fermentations aimed at increased aromatics production, but also deepen our understanding of yeast metabolism.
authors: Centre for Microbial Electrosynthesis (CEMES), University of Queensland, Brisbane, Australia.
authors: Gal
authors: G
authors: Winter
authors: Nils J H
authors: NJ
authors: Averesch
authors: Dariela
authors: D
authors: Nunez-Bernal
authors: Jens O
authors: JO
authors: Krömer
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D002827:Chorismic Acid / Q000737:chemistry* / Q000378:metabolism*; D003509:Cyclohexanecarboxylic Acids / Q000378:metabolism; D053138:Cyclohexenes / Q000378:metabolism; D005285:Fermentation; D017353:Gene Deletion; D060847:Metabolic Engineering; D010649:Phenylalanine / Q000096:biosynthesis*; D010667:Phenylpyruvic Acids / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
chemical_list: D003509:Cyclohexanecarboxylic Acids; D053138:Cyclohexenes; D010667:Phenylpyruvic Acids; D010649:Phenylalanine; D002827:Chorismic Acid; C031606:phenylpyruvic acid; C005550:prephenic acid
keywords: PABA; PHBA; Saccharomyces; aromatics; chorismate; paraaminobezoic acid; parahydroxybenzoic acid; phenylalnine; phenylpyruvate