title: Zeolin. A new recombinant storage protein constructed using maize gamma-zein and bean phaseolin.
abstract: The major seed storage proteins of maize (Zea mays) and bean (Phaseolus vulgaris), zein and phaseolin, accumulate in the endoplasmic reticulum (ER) and in storage vacuoles, respectively. We show here that a chimeric protein composed of phaseolin and 89 amino acids of gamma-zein, including the repeated and the Pro-rich domains, maintains the main characteristics of wild-type gamma-zein: It is insoluble unless its disulfide bonds are reduced and forms ER-located protein bodies. Unlike wild-type phaseolin, the protein, which we called zeolin, accumulates to very high amounts in leaves of transgenic tobacco (Nicotiana tabacum). A relevant proportion of the ER chaperone BiP is associated with zeolin protein bodies in an ATP-sensitive fashion. Pulse-chase labeling confirms the high affinity of BiP to insoluble zeolin but indicates that, unlike structurally defective proteins that also extensively interact with BiP, zeolin is highly stable. We conclude that the gamma-zein portion is sufficient to induce the formation of protein bodies also when fused to another protein. Because the storage proteins of cereals and legumes nutritionally complement each other, zeolin can be used as a starting point to produce nutritionally balanced and highly stable chimeric storage proteins.
authors.affiliation: Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche, 20133 Milano, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Mainieri
authors.forename: Marika
authors.initials: M
authors.lastname: Rossi
authors.forename: Marco
authors.initials: M
authors.lastname: Archinti
authors.forename: Michele
authors.initials: M
authors.lastname: Bellucci
authors.forename: Francesca
authors.initials: F
authors.lastname: De Marchis
authors.forename: Stefano
authors.initials: S
authors.lastname: Vavassori
authors.forename: Andrea
authors.initials: A
authors.lastname: Pompa
authors.forename: Sergio
authors.initials: S
authors.lastname: Arcioni
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vitale
mesh_terms: D000595:Amino Acid Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism; D027805:Phaseolus; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D003313:Zea mays; D015028:Zein / Q000378:metabolism*
chemical_list: D046912:Multiprotein Complexes; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C048826:phaseolin protein, Phaseolus vulgaris; D015028:Zein