title: PHO13 deletion-induced transcriptional activation prevents sedoheptulose accumulation during xylose metabolism in engineered Saccharomyces cerevisiae.
abstract: The deletion of PHO13 (pho13Δ) in Saccharomyces cerevisiae, encoding a phosphatase enzyme of unknown specificity, results in the transcriptional activation of genes related to the pentose phosphate pathway (PPP) such as TAL1 encoding transaldolase. It has been also reported that the pho13Δ mutant of S. cerevisiae expressing a heterologous xylose pathway can metabolize xylose efficiently compared to its parental strain. However, the interaction between the pho13Δ-induced transcriptional changes and the phenotypes of xylose fermentation was not understood. Thus we investigated the global metabolic changes in response to pho13Δ when cells were exponentially growing on xylose. Among the 134 intracellular metabolites that we identified, the 98% reduction of sedoheptulose was found to be the most significant change in the pho13Δ mutant as compared to its parental strain. Because sedoheptulose-7-phosphate (S7P), a substrate of transaldolase, reduced significantly in the pho13Δ mutant as well, we hypothesized that limited transaldolase activity in the parental strain might cause dephosphorylation of S7P, leading to carbon loss and inefficient xylose metabolism. Mutants overexpressing TAL1 at different degrees were constructed, and their TAL1 expression levels and xylose consumption rates were positively correlated. Moreover, as TAL1 expression levels increased, intracellular sedoheptulose concentration dropped significantly. Therefore, we concluded that TAL1 upregulation, preventing the accumulation of sedoheptulose, is the most critical mechanism for the improved xylose metabolism by the pho13Δ mutant of engineered S. cerevisiae.
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
authors.forename: Haiqing
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Biotechnology, Graduate School, Korea University, Seoul, Korea.
authors.forename: Sooah
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Chemistry, University of California, Berkeley, USA.
authors.forename: Hagit
authors.initials: H
authors.lastname: Sorek
authors.affiliation: School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea.
authors.forename: Youngsuk
authors.initials: Y
authors.lastname: Lee
authors.affiliation: School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea.
authors.forename: Deokyeol
authors.initials: D
authors.lastname: Jeong
authors.affiliation: Department of Biotechnology, Graduate School, Korea University, Seoul, Korea.
authors.forename: Jungyeon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
authors.forename: Eun Joong
authors.initials: EJ
authors.lastname: Oh
authors.affiliation: Department of Biotechnology, Graduate School, Korea University, Seoul, Korea.
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Yun
authors.affiliation: Department of Chemistry, University of California, Berkeley, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Wemmer
authors.affiliation: Department of Biotechnology, Graduate School, Korea University, Seoul, Korea.
authors.forename: Kyoung Heon
authors.initials: KH
authors.lastname: Kim
authors.affiliation: School of Food Science and Biotechnology, Kyungpook National University, Daegu, Korea. Electronic address: soorinkim@knu.ac.kr.
authors.forename: Soo Rin
authors.initials: SR
authors.lastname: Kim
authors.affiliation: Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA. Electronic address: ysjin@illinois.edu.
authors.forename: Yong-Su
authors.initials: YS
authors.lastname: Jin
mesh_terms: D004789:Enzyme Activation; D020868:Gene Silencing; D024861:Genetic Enhancement / Q000379:methods; D006539:Heptoses / Q000235:genetics / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D014994:Xylose / Q000378:metabolism*
chemical_list: D006539:Heptoses; D029701:Saccharomyces cerevisiae Proteins; C003011:sedoheptulose; D014994:Xylose; C000602301:Pho13 protein, S cerevisiae; D010744:Phosphoric Monoester Hydrolases
keywords: Cas9-guided genome editing technique; GC-TOF/MS; Metabolomics; NMR; RNA-seq