| In previous work,the secondary metabolites of Stereum hirsutum were investigated by One Strain Many Compounds(OSMAC)method,and novel compounds with antibacterial activity obtained.In order to further explore the secondary metabolites of Stereum hirsutum,we selected three PKS gene(PKS1,PKS2 and PKS3)which maybe silent or low expression in natural cultural conditions,and annotated those functions and predicted possible metabolites by antiSMASH,InterPro and Blast,CDD database analysis The results are as follows:1.Three PKS genes(PKS1,PKS2 and PKS3)were annotated those functions and predicted possible metabolites.By analyzing PKS1 and PKS2,the functional domains were similar very much except of one ACP module.Their homologies are61.8%,and PKS1 and PKS2 maybe participate in biosynthesis of orsellinic acid.PKS3 may be an atypical mushroom polyketide synthase and can participate in the biosynthesis of polyunsaturated fatty acids.2.Heterologous expression vectors were constructed on basis of pRS314 and pBARGPE1-Hygro-EGFP in Saccharomyces cerevisiae.The vectors can be stable at low copy in Saccharomyces cerevisiae,which contained a strong endogenous promoter gpdA.3.The cultural extracts of heterogenous expression mutants were detected and analyzed by TLC and LC-MS.Comparison with the control,the extracts of SC-pYUZ03 andSC-pYUZ04 mutant were no obvious difference with control by TLC analysis;and the extracts of SC-pYUZ05 mutant showed an obvious orange-red dot by the color of bismuth potassium iodide.Then by LC-MS,the extracts of mutant containing SC-pYUZ03 showed no difference with control;the SC-pYUZ04 mutant showed an enhance peak.In the LC-MS profiles of SC-pYUZ05 extracts,four additional peaks were found at positive mode,and they are at 253,287,483 and 617,respectively. |
