title: Plastid localization of the key carotenoid enzyme phytoene synthase is altered by isozyme, allelic variation, and activity.
abstract: Plant carotenoids have unique physiological roles related to specific plastid suborganellar locations. Carotenoid metabolic engineering could enhance plant adaptation to climate change and improve food security and nutritional value. However, lack of fundamental knowledge on carotenoid pathway localization limits targeted engineering. Phytoene synthase (PSY), a major rate-controlling carotenoid enzyme, is represented by multiple isozymes residing at unknown plastid sites. In maize (Zea mays), the three isozymes were transiently expressed and found either in plastoglobuli or in stroma and thylakoid membranes. PSY1, with one to two residue modifications of naturally occurring functional variants, exhibited altered localization, associated with distorted plastid shape and formation of a fibril phenotype. Mutating the active site of the enzyme reversed this phenotype. Discovery of differential PSY locations, linked with activity and isozyme type, advances the engineering potential for modifying carotenoid biosynthesis.
authors.affiliation: Department of Biological Sciences, Lehman College, City University of New York, Bronx, NY 10468, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Shumskaya
authors.forename: Louis M T
authors.initials: LM
authors.lastname: Bradbury
authors.forename: Regina R
authors.initials: RR
authors.lastname: Monaco
authors.forename: Eleanore T
authors.initials: ET
authors.lastname: Wurtzel
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D002338:Carotenoids / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D007527:Isoenzymes; D058503:Mesophyll Cells; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012275:Oryza / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000201:enzymology / Q000235:genetics / Q000648:ultrastructure; D021381:Protein Transport; D003313:Zea mays / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D002338:Carotenoids; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase