Detection and Expression of Biosynthetic Genes in Actinobacteria ...

BERVANAKIS, G.Chapter 1: INTRODUCTIONTable 6. Examples of genes for pathway-specific regulators in the biosynthesis ofsecondary metabolites in actinobacteria.Genes forCommentsReferencespathwayspecificregulatorsbrpAmmyRStreptomyces hygroscopicus mutant blockedin bialaphos production and accumulation ofbap transcripts.Mutant overproduces methylenomycinAnzai et al., 1987Chater, 1992redD Mutants cause loss of undecylprodigiosin Takano et al., 1992productionactII-ORF4strRMutants cause loss of actinorhodinproduction. Accumulation if act transcriptsreduced in mutants.Required for expression of at least one strFernández-Moreno et al.,1991Distler et al., 1992dnrIgene in Streptomyces griseus.Streptomyces peucetius mutant blocked indaunorubicin productionStutzman-Engwall et al.,19921.4.1.1 TranscriptionProkaryotic genes are regulated at the level of transcription enabling bacteria toalternate gene expression expediently and economically (Shinkawa, 1996). Geneexpression systems for secondary metabolite biosynthesis in actinobacteria haveFigure 14. Diagram depicting the regulatory network in response to a stimulus andthe changes accompanying a cells activities and functions. The cell first sensors oneor more stimuli. The sensor communicates the stimuli to a response regulator,resulting in altered transcription of target operons, altered levels of messengerribonucleic acids (mRNAs), changes in the synthesis of proteins and alterations inactivities and functions. Each of these stages can be affected by feedback, as indicatedby dashed arrows (adapted from VanBogelen et al., 1999)._____________________________________________________________________25