title: An Untranslated cis-Element Regulates the Accumulation of Multiple C4 Enzymes in Gynandropsis gynandra Mesophyll Cells.
abstract: C4 photosynthesis is a complex phenotype that allows more efficient carbon capture than the ancestral C3 pathway. In leaves of C4 species, hundreds of transcripts increase in abundance compared with C3 relatives and become restricted to mesophyll (M) or bundle sheath (BS) cells. However, no mechanism has been reported that regulates the compartmentation of multiple enzymes in M or BS cells. We examined mechanisms regulating CARBONIC ANHYDRASE4 (CA4) in C4 Gynandropsis gynandra. Increased abundance is directed by both the promoter region and introns of the G. gynandra gene. A nine-nucleotide motif located in the 5' untranslated region (UTR) is required for preferential accumulation of GUS in M cells. This element is present and functional in three additional 5' UTRs and six 3' UTRs where it determines accumulation of two isoforms of CA and pyruvate,orthophosphate dikinase in M cells. Although the GgCA4 5' UTR is sufficient to direct GUS accumulation in M cells, transcripts encoding GUS are abundant in both M and BS. Mutating the GgCA4 5' UTR abolishes enrichment of protein in M cells without affecting transcript abundance. The work identifies a mechanism that directs cell-preferential accumulation of multiple enzymes required for C4 photosynthesis.
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Ben P
authors.identifier: http://orcid.org/0000-0002-2002-1410
authors.initials: BP
authors.lastname: Williams
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Burgess
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Ivan
authors.initials: I
authors.lastname: Reyna-Llorens
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Jana
authors.initials: J
authors.lastname: Knerova
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Sylvain
authors.identifier: http://orcid.org/0000-0002-7598-3609
authors.initials: S
authors.lastname: Aubry
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
authors.forename: Susan
authors.initials: S
authors.lastname: Stanley
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom jmh65@cam.ac.uk.
authors.forename: Julian M
authors.identifier: http://orcid.org/0000-0003-0662-7958
authors.initials: JM
authors.lastname: Hibberd
mesh_terms: D002256:Carbonic Anhydrases / Q000235:genetics / Q000378:metabolism; D031485:Cleome / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D017930:Genes, Reporter; D007438:Introns / Q000235:genetics; D058503:Mesophyll Cells / Q000201:enzymology; D010788:Photosynthesis / Q000235:genetics; D018515:Plant Leaves / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D016415:Sequence Alignment; D020506:Untranslated Regions / Q000235:genetics
chemical_list: D010940:Plant Proteins; D020506:Untranslated Regions; D002256:Carbonic Anhydrases