1987•Unpublished venueRequires access
Functional Expression ofPlastid Allophycocyanin Genesina Cyanobacteriumt
Robertde Lorimier, Gérard Guglielmi
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Abstract
InCyanophora paradoxa, theallophycocyanin apoprotein subunits, a andjS, areencoded inthecyanelle (plastid) genome. These geneswere transferred tothecyanobacterium Synechococc4s sp.PCC 7002on a plasmid replicon.Phycobilisomes isolated fromtransformed cyanobacteria werefoundtocontain C.paradoxa allophycocyanin subunits. Thus, these plastid genesareexpressed inthecyanobacterium aspolypeptides which becomelinked toa chromophore andareincorporated intothelight-harvesting apparatus. Thephycobiliproteins comprise a large fraction ofthe photosynthetic light-harvesting capacity inredalgae and cyanobacteria. Thesepolypeptides arelinked covalently to linear tetrapyrrole chromophores andareorganized into supramolecular complexes called phycobilisomes (for areview, seereference 9).Allophycocyanin (AP)isthemajor phycobiliprotein foundinthecoresubstructure ofall phycobilisomes. Itconsists oftwosubunits, designated a and,f, eachapproximately 17kilodaltons inmassandeach witha single phycocyanobilin chromophore boundtoa cysteine residue oftheapoprotein. Attached tothecoreand radiating outward fromitarerodsubstructures composed of phycocyanin (PC)andoften other phycobiliproteins. Light