In Saccharomyces cerevisiae, when l-phenylalanine (l-Phe) is used as the sole nitrogen source, 2-phenylethanol (PE) is mainly synthesized via the Ehrlich pathway. General amino acid permease Gap1p is response of aromatic amino acids transportation, and GATA transcription factors Gln3p and Gat1p regulate the transcription of permease gene and catabolic enzyme genes for nitrogen sources and aromatic amino acids utilization. In this study, it was demonstrated that over-expressing GLN3 gene from industrial yeast strain MT2 or S. cerevisiae haploid strain YS58, 2-PE synthesis levels of recombinant strains increased 54% or 40% than that of the control strain, which suggested that higher Gln3p activity in yeast has positive regulation effect on 2-PE biosynthesis via Ehrlich pathway. The recombinant strains with over-expression of GAT1 gene from MT2 or YS58 also up-regulated Ehrlich pathway for 2-PE biosynthesis and increased 2-PE production. Similarly, when GAP1 gene respectively from MT2 or YS58 was over-expressed, 2-PE yield was improved obviously, suggesting that GAP1 over-expressing in yeast also promoted Ehrlich pathway to produce 2-PE. The synergistic regulation of GLN3/GAT1 or GLN3/GAP1 over-expression was similar to that of single factor over-expression. Among these regulatory factors, Gln3p of industrial yeast strain MT2 caused stronger regulation on target genes than that of haploid strain YS58, which might be due to the differences in translational efficiency or nuclear localization of each Gln3p, or due to their different spatial structures and binding domains. Further results showed that efficient Gln3p expression in MT2 brought about higher 2-PE, 3.59gL^-1, which was of potential significant for commercial exploitation.

• PMID: 27908775
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Journal Article

Authors

Chen X, Wang Z, Guo X, Liu S, He X

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