Genetic control of a membrane component and zein deposition in maize endosperm

Galante, E; Vitale, Alessandro; Manzocchi, Lucia A.; Soave, C.; Salamini, F.

doi:10.1007/bf00392168

Cited by 28 publications

(14 citation statements)

References 26 publications

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“…We therefore established whether zeolin also forms protein bodies. In maize endosperm, the ER-located zein protein bodies are spherical structures with a diameter between 0.3 and 1.4 mm, depending on the stage of seed development (Lending and Larkins, 1989) and with a density around 1.21 to 1.22 g/ mL (Hurkman et al, 1981;Galante et al, 1983). Young leaves from transgenic tobacco were homogenized in a buffer in the absence of detergent and the presence of Suc and the subcellular compartments were fractionated by isopycnic ultracentrifugation in Suc gradients.…”

Section: Zeolin Forms Protein Bodiesmentioning

confidence: 99%

Zeolin. A New Recombinant Storage Protein Constructed Using Maize γ-Zein and Bean Phaseolin

et al. 2004

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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 γ-zein, including the repeated and the Pro-rich domains, maintains the main characteristics of wild-type γ-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 γ-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.

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Section: Zeolin Forms Protein Bodiesmentioning

confidence: 99%

Zeolin. A New Recombinant Storage Protein Constructed Using Maize γ-Zein and Bean Phaseolin

et al. 2004

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“…In the mutants associated with ER stress, molecular chaperones have been found in association with protein bodies, which are the predominant location of the mutant zeins (Galante et al, 1983;Zhang and Boston, 1992). To determine whether Zm Derlins similarly localized preferentially to protein bodies in endosperm of ER stress mutants, we separated ER into cisternal and protein body fractions .…”

Section: Zm Derlin1 and Zm Derlin2 Proteins Associate With Protein Bomentioning

confidence: 99%

Identification and Characterization of Endoplasmic Reticulum-Associated Degradation Proteins Differentially Affected by Endoplasmic Reticulum Stress

et al. 2005

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The disposal of misfolded proteins from the lumen of the endoplasmic reticulum (ER) is one of the quality control mechanisms present in the protein secretory pathway. Through ER-associated degradation, misfolded substrates are targeted to the cytosol where they are degraded by the proteasome. We have identified four maize (Zea mays) Der1-like genes (Zm Derlins) that encode homologs of Der1p, a yeast (Saccharomyces cerevisiae) protein implicated in ER-associated degradation. Zm Derlins are capable of functionally complementing a yeast Der1 deletion mutant. Such complementation indicates that the Der1p function is conserved among species. Zm Derlin genes are expressed at low levels throughout the plant, but appear prevalent in tissues with high activity of secretory protein accumulation, including developing endosperm cells. Expression of three of the four Zm Derlin genes increases during ER stress, with Zm Derlin1-1 showing the strongest induction. Subcellular fractionation experiments localized Zm Derlin proteins to the membrane fraction of microsomes. In maize endosperm, Zm Derlin proteins were found primarily associated with ER-derived protein bodies regardless of the presence of an ER stress response.The endoplasmic reticulum (ER) serves as a versatile gatekeeper of the secretory pathway. It is not only the entry point for translocation of newly synthesized proteins, but also the site of quality control processes that discriminate between conformationally correct proteins in a native state and those that are terminally misfolded. In the latter case, continued protein accumulation could be toxic to the organism, possibly impairing its development. To cope with the accumulation of misfolded proteins and restore homeostasis, the cell initiates an ER stress response that has been linked to development of ER-rich tissues, upregulation of molecular chaperones, selective translational attenuation, and activation of an ER-associated degradation (ERAD) process (Zhang and Kaufman, 2004). ERAD ensures that aberrant proteins do not transit through the secretory pathway. Instead, misfolded proteins are targeted for removal from this pathway by retrotranslocation through the ER membrane to the cytosol where they undergo ubiquitination and degradation by the proteasome (Brodsky and McCracken, 1999;McCracken and Brodsky, 2003).Attempts to characterize the ERAD process have allowed identification of several components of the ERAD machinery, some of which are co-opted from their classical roles in importing proteins to additional functions in protein export. Genetic studies are consistent with a model whereby molecular chaperones could present ERAD substrates to the Sec61 complex (Nishikawa et al., 2001;Molinari et al., 2002). Upon association of ERAD components, the Sec61 complex would form a channel for retrotranslocation of the misfolded proteins . Proteins emerging from the ER would be ubiquitinated by the combined action of ubiquitin-conjugating enzymes (ubc6, ubc1, and/or ubc7) and the ubiquitin-ligase complex Hrd1/Der3....

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“…The synthesis of plant BiP is induced by tunicamycin (D'Amico et aL, 1992;Denecke et al, 1991;Fontes et al, 1991) and is also constitutively enhanced in the endosperm of some of the maize mutants that accumulate reduced amounts of the ER-Iocated storage protein zein Galante et al, 1983;Marocco et aL, 1991), suggesting that these mutants may synthesize zein polypeptides with structural defects. Immunolocalization shows that in the mutants there is increased accumulation of BiP at the periphery of the zein-containing protein bodies (Zhang and Boston, 1992).…”

Section: Introductionmentioning

confidence: 99%

Binding of BiP to an assembly‐defective protein in plant cells

et al. 1994

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SummaryThe binding protein (BiP) has been implicated as a mediator of protein folding and assembly in the endoplasmic reticulum of mammalian cells and has often been found in stable association with structurally defective proteins. To acquire information on the activity of BiP in plant cells, we have expressed in tobacco protoplasts the wild type form and an assembly-defective form of bean phaseolin. Phaseolin (PHSL) is a soluble, trimeric, storage glycoprotein co-translationally inserted into the lumen of the endoplasmic reticulum and then transported along the secretory pathway to the protein storage vacuoles. We have previously shown that a PHSL mutant in which the last 59 amino acids have been deleted (A363PHSL) is unable to form trimers and is retained in a pre-Golgi compartment when synthesized in Xenopus oocytes. When transiently expressed in tobacco leaf protoplasts, wild-type PHSL is correctly glycosylated and assembles efficiently and rapidly into trimers. A363PHSL is also correctly glycosylated but does not trimerize. Tobacco BiP and A363PHSL are co-immunoselected using either anti-PHSL or anti-BiP antibodies. Under the same conditions, co-immunoselection of BiP with wild-type PHSL is not detectable. The BiP bound to A363PHSL can be released by treatment of the complex with ATP, indicating that the binding is related to the proposed function of BiP in protein folding and assembly in the endoplasmic reticulum. These data indicate that BiP stably binds structurally defective proteins in plant cells.

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Genetic control of a membrane component and zein deposition in maize endosperm

Cited by 28 publications

References 26 publications

Zeolin. A New Recombinant Storage Protein Constructed Using Maize γ-Zein and Bean Phaseolin

Zeolin. A New Recombinant Storage Protein Constructed Using Maize γ-Zein and Bean Phaseolin

Identification and Characterization of Endoplasmic Reticulum-Associated Degradation Proteins Differentially Affected by Endoplasmic Reticulum Stress

Binding of BiP to an assembly‐defective protein in plant cells

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