Cyanophage regulatory elements are functional in the plastid environment, allowing the expression of heterologous proteins

MIRKIN, FEDERICO GABRIEL; JUAREZ, MARCELO; BOCCARDO, NOELIA AYELEN; BRAVO-ALMONACID, FERNANDO FELIX; SEGRETIN, MARÍA EUGENIA

Congreso; XXXII Reunión Argentina de Fisiología Vegetal y XV Congreso Latinoamericano de Fisiología Vegetal; 2018

Theexpression of heterologous proteins bythetransformation ofthe plastid genomeis an interesting biotechnologicalstrategy duetothe potentially high expression levels(up to70% of total soluble proteins). Only a few regulatory elements have proved to beefficient promoting theexpressionof transgenesin thisorganelle. Becauseof itsevolutionaryorigin, chloroplasts share many characteristics with theircyanobacteria ancestors, including many aspects of generegulation.Toevaluateifregulatoryelementsofcyanophage(bacteriophagesthat infectcyanobacteria)origin arefunctional in the plastidialenvironment,westudied the promoterand 5?UTR ofthe psbA geneofthecyanophage S-PM2 in tobaccochloroplasts. In order to dothis, wecloned thesesequences in a plastid transformation vector upstream theuidA reporter gene and we transformed tobacco plastids.Bacteria and transplastomic plantsthatexpress b-glucuronidase under the regulatory control of (1) tobacco psbApromoter and 5?UTR,(2)tobacco psbA promoter and S-PM2psbA 5?UTR, and (3) S-PM2 psbA promoter and 5?UTR arebeing evaluated, to determinefunctionalityof S-PM2 regulatoryelementsto allowtranscription and/or promotetranslation in the plastidial environment. We will be presentingresults showing that cyanophage regulatory elements arefunctional in plastidsof higher plants.