Comparative proteome analysis of Hansenula polymorpha DL1 and A16

Proteomic responses of methylotrophic yeasts (Hansenula polymorpha DL1 and A16) to growth medium tuning by carbon source shift (glycerol-->methanol) were monitored and analyzed by two-dimensional gel electrophoresis. Through comparative analyses of two-dimensional gels, intracellular yeast proteins with complex expression patterns were systematically sorted into: (1) proteins that are commonly expressed with comparable high abundance in both strains; (2) strain-specific proteins that are expressed at high level only in a particular strain; (3) strain-specific and methanol-induced proteins that are expressed only in the presence of methanol; and (4) strain-specific and constitutively-expressed proteins that are expressed consistently irrespective of carbon source shift without extreme change in expression level. Among the DL1-specific proteins belonging to group four, the four proteins showing the highest expression levels in the course of the fermentation process were identified as: glucose-6-phosphate dehydrogenase, isocitrate lyase, succinyl-CoA synthetase, and glycerol-3-phosphate dehydrogenase. From these results, it is suggested that DL1 has distinct metabolic characteristics including enhanced metabolic activities both in glycerol uptake and the glyoxylate bypass cycle, as compared to A16. This is likely to explain why the DL1 strain shows a significantly higher rate of glycerol and methanol consumption during the fermentation process. Our systematic approach to the analysis of proteomic responses and the detailed analysis results reported here will be useful to better understand the global physiology of H. polymorpha, as proteome databases for various methylotrophic yeasts are established.