title: Reduction of PDC1 expression in S. cerevisiae with xylose isomerase on xylose medium.
abstract: Ethanol production using hemicelluloses has recently become a focus of many researchers. In order to promote D: -xylose fermentation, we cloned the bacterial xylA gene encoding for xylose isomerase with 434 amino acid residues from Agrobacterium tumefaciens, and successfully expressed it in Saccharomyces cerevisiae, a non-xylose assimilating yeast. The recombinant strain S. cerevisiae W303-1A/pAGROXI successfully colonized a minimal medium containing D: -xylose as a sole carbon source and was capable of growth in minimal medium containing 2% xylose via aerobic shake cultivation. Although the recombinant strain assimilates D: -xylose, its ethanol productivity is quite low during fermentation with D: -xylose alone. In order to ascertain the key enzyme in ethanol production from D: -xylose, we checked the expression levels of the gene clusters involved in the xylose assimilating pathway. Among the genes classified into four groups by their expression patterns, the mRNA level of pyruvate decarboxylase (PDC1) was reduced dramatically in xylose media. This reduced expression of PDC1, an enzyme which converts pyruvate to acetaldehyde, may cause low ethanol productivity in xylose medium. Thus, the enhancement of PDC1 gene expression may provide us with a useful tool for the fermentation of ethanol from hemicellulose.
authors: BK21 Ubiquitous Information Appliances, Chonnam National University, Gwangju, 500-757, Korea.
authors: Dong Min
authors: DM
authors: Kim
authors: Seung-Hyun
authors: SH
authors: Choi
authors: Byung Sam
authors: BS
authors: Ko
authors: Gwon-Young
authors: GY
authors: Jeong
authors: Han-Bit
authors: HB
authors: Jang
authors: Jae-Gun
authors: JG
authors: Han
authors: Kyung-Hwan
authors: KH
authors: Jeong
authors: Hyeon-Yong
authors: HY
authors: Lee
authors: Yonggwan
authors: Y
authors: Won
authors: Il-Chul
authors: IC
authors: Kim
mesh_terms: D060054:Agrobacterium / Q000201:enzymology / Q000235:genetics; D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D000431:Ethanol / Q000302:isolation & purification / Q000378:metabolism*; D011767:Pyruvate Decarboxylase / Q000096:biosynthesis* / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D014162:Transfection; D014994:Xylose / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000431:Ethanol; D014994:Xylose; C101504:PDC1 protein, S cerevisiae; D011767:Pyruvate Decarboxylase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase