Peroxisomes and peroxisomal transketolase and transaldolase enzymes are essential for xylose alcoholic fermentation by the methylotrophic thermotolerant yeast, Ogataea (Hansenula) polymorpha.

摘要: Ogataea (Hansenula) polymorpha is one of the most thermotolerant xylose-fermenting yeast species reported to date. Several metabolic engineering approaches have been successfully demonstrated improve high-temperature alcoholic fermentation by O. polymorpha. Further improvement ethanol production from xylose in depends on identification bottlenecks conversion pathway ethanol. Involvement peroxisomal enzymes metabolism has not described Here, we found that transketolase (known also as dihydroxyacetone synthase) and transaldolase (enzyme with unknown function) methylotrophic yeast, polymorpha, are required for fermentation, but growth this pentose sugar. Mutants knockout DAS1 TAL2 coding transaldolase, respectively, normally grow xylose. However, these mutants were be unable support production. The mutant TAL1 (coding cytosolic transaldolase) grew glucose did xylose; defect was rescued overexpression TAL2. conditional mutant, pYNR1-TKL1, expresses gene under control ammonium repressible nitrate reductase promoter poorly media supplemented ammonium. Overexpression only partially restored defects displayed pYNR1-TKL1 mutant. defective peroxisome biogenesis, pex3Δ pex6Δ, showed normal xylose, ferment Moreover, non-methylotrophic Scheffersomyces (Pichia) stipitis, grows ferments Separate or co-overexpression wild-type strain increased synthesis 2 4 times no effect glucose. TKL1 elevated Finally, best previously isolated producer led increase accumulation up 16.5 g/L at 45 °C; 30–40 times more than produced strain. Our results indicate importance enzymes, (dihydroxyacetone synthase, Das1), (Tal2),