Transcriptomic Analysis Of Impacts Of Glycerol On Methanol Metabolism In Pichia Pastoris

The efficient promoter of alcohol oxidase 1(P_AOX1)in methylotrophic yeast Pichia pastoris is strictly induced by methanol but repressed by glycerol with an unclear molecular mechanism.In the present study,the gene of a previously characterized transmembrane protein glycerol transporter 1（GT1）of P.pastoris GS115 was deleted by homologous recombination.Transcriptional profiles of the mutant（GT1?）and wild type（WT）were compared with different carbon sources（glycerol,methanol and glycerol–methanol mix）at various time points using high-throughput RNA-Seq techniques.The principal results are as follows:（1）It was determined that the loss of glycerol transporter 1（GT1）could relieve catabolite repression in the glycerol–methanol mixed medium and shared a similar transcriptional profile with the WT in methanol medium.（2）By calculating the common differentially expressed genes（DEGs）in three distinct paired groups,genes involved in the stress response,nutrition deprivation and translational process were identified,explaining the potential roles of glycerol in the regulation of methanol metabolism.（3）Based on weighted gene co-expression network analysis（WGCNA）,the relationship between biological traits and the transcriptional profile was established.A gene module called‘MEmagenta’was discovered,which was close to methanol metabolism and involved in biological processes such as carbohydrate metabolism,energy metabolism and signal transduction.（4）With the support of published research and transcriptome data,two possible regulatory pathways was proposed that are involved in the regulation of catabolite repression（AMPK/SNF1 and MAPK/HOG）,thereby providing potential targets for both research and industrial strain improvement.（5）The keys genes（ZRT1,HOT1 and SUT2）involved in catabolite repression was discovered,and the efficiency of SUT2 could result in derepression in glycerol medium,therefore providing reference for following works.