Structure and biosynthesis of the xylose‐containing carbohydrate moiety of rice α‐amylase

Hayashi, Makoto; Tsuru, Akiko; Mitsui, Toshiaki; Takahashi, Nobutaka; Hanzawa, Hiroyuki; Arata, Yoshiaki; Akazawa, Takashi

doi:10.1111/j.1432-1033.1990.tb19122.x

Cited by 52 publications

(19 citation statements)

References 42 publications

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“…According to the present results that clearly indicate in which Golgi compartment most PI +2 xylose and a1 +3 fucose residues are added to plant complex glycans and considering what has already been published on N-glycosylation in rice (Hayashi et al, 1990), bean (Sturm et a/., 1987) and sycamore (Tezuka et al, 1992), we propose a model for plant N-linked glycan processing in the Golgi apparatus. After a trimming of three glucoses and possibly one mannose residue in the ER, the glycoprotein is transported through the cis and the medial cisternae of the Golgi apparatus where the glycan can progressively be further matured to a G I C N A~~M~~, ( G I C N A C )~ structure.…”

Section: Discussionsupporting

confidence: 76%

Distribution of xylosylation and fucosylation in the plant Golgi apparatus

et al. 1994

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SummaryAntibodies have been immunopurified which are specific for carbohydrate epitopes containing the pl+2 xylose or a1 4 3 fucose residues found on complex Nlinked glycans in plants. The antibody specificity was determined by taking advantage of an Arabidopsis thaliana N-glycosylation mutant which lacks N-acetylglucosaminyltransferase I and is unable to synthesize complex glycans. These antibodies were used to immunolocalize xylose-and fucose-containing glycoproteins in suspension-cultured sycamore cells (Acer pseudoplatanus). By mapping the enzymatic reaction products within the Golgi apparatus, the fucosyl-and xylosyltransferase subcellular localization was made possible using immunocytochemistry on thin sections of high-pressure frozen and freezesubstituted sycamore cells. This procedure allows a much better preservation of organelles, and particularly of the Golgi stack morphology, than that obtained with conventionally fixed samples. Glycoproteins containing p1+2 xylose and al+3 fucose residues were immunodetected in the cell wall, the vacuole, and the Golgi cisternae. The extent of immunolabeling over the different cisternae of 50 Golgi stacks was quantified after treatment with antixylose or anti-fucose antibodies. Labeling for xylosecontaining glycoproteins was predominent in the medial cisternae, while fucose-containing glycoproteins were mainly detected in the trans compartment. Therefore, in plants, complex N-linked glycan xylosylation probably occurs mostly at the medial Golgi level and a1 4 3 fucose is mainly incorporated in the trans cisternae. Finally, fucose-and xylosecontaining glycoproteins were also immunolocalized, albeit to a lesser extent, in earlier Golgi compartments. This indicates that the glycosylation events are a continuous process with some maxima in given compartments, rather than a succession of discrete and compartment-dependent steps.

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Section: Discussionsupporting

confidence: 76%

Distribution of xylosylation and fucosylation in the plant Golgi apparatus

et al. 1994

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“…The presence of a typical N-terminal signal peptide for ER membrane translocation was confirmed in all precursor forms of these isoforms. The oligosaccharide structure and its conjugating site for AmyI-1 have been determined (Hayashi et al, 1990;Terashima et al, 1994). Thus, there is no doubt that AmyI-1 is a secretory glycoprotein.…”

Section: Amyi-1 Degrades Starch Granules In Living Rice Cellsmentioning

confidence: 99%

“…In germinating cereal seeds, these enzyme molecules are biosynthesized and secreted from the secretory tissues, the scutellar epithelium and the aleurone, to the starchy endosperm, which has undergone programmed cell death. Numerous a-amylase isoforms have been identified in cereals, but the predominant a-amylase isoform I-1 (AmyI-1) in rice (Oryza sativa) is a unique glycoprotein that bears N-linked oligosaccharide side chains (Hayashi et al, 1990;Terashima et al, 1994). The biosynthesis and secretion of AmyI-1 have been extensively investigated: mRNA translation on endoplasmic reticulum (ER) membrane-bound ribosomes, signal sequence-dependent translocation of the ER, core glycosylation in the ER lumen, vesicular transport to the Golgi apparatus, oligosaccharide modification to the complex type, and exocytosis all proceed according to the canonical secretory mechanism (Palade, 1975;Blobel, 1980;Kornfeld and Kornfeld, 1985).…”

Section: Introductionmentioning

confidence: 99%

The Rice α-Amylase Glycoprotein Is Targeted from the Golgi Apparatus through the Secretory Pathway to the Plastids

et al. 2009

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The well-characterized secretory glycoprotein, rice (Oryza sativa) a-amylase isoform I-1 (AmyI-1), was localized within the plastids and proved to be involved in the degradation of starch granules in the organelles of rice cells. In addition, a large portion of transiently expressed AmyI-1 fused to green fluorescent protein (AmyI-1-GFP) colocalized with a simultaneously expressed fluorescent plastid marker in onion (Allium cepa) epidermal cells. The plastid targeting of AmyI-1 was inhibited by both dominant-negative and constitutively active mutants of Arabidopsis thaliana ARF1 and Arabidopsis SAR1, which arrest endoplasmic reticulum-to-Golgi traffic. In cells expressing fluorescent trans-Golgi and plastid markers, these fluorescent markers frequently colocalized when coexpressed with AmyI-1. Three-dimensional time-lapse imaging and electron microscopy of high-pressure frozen/freeze-substituted cells demonstrated that contact of the Golgi-derived membrane vesicles with cargo and subsequent absorption into plastids occur within the cells. The transient expression of a series of C-terminal-truncated AmyI-1-GFP fusion proteins in the onion cell system showed that the region from Trp-301 to Gln-369 is necessary for plastid targeting of AmyI-1. Furthermore, the results obtained by site-directed mutations of Trp-302 and Gly-354, located on the surface and on opposite sides of the AmyI-1 protein, suggest that multiple surface regions are necessary for plastid targeting. Thus, Golgi-to-plastid traffic appears to be involved in the transport of glycoproteins to plastids and plastid targeting seems to be accomplished in a sorting signal-dependent manner. INTRODUCTIONCereal a-amylases (EC 3.2.1.1) are typical secretory proteins found in many plants. In germinating cereal seeds, these enzyme molecules are biosynthesized and secreted from the secretory tissues, the scutellar epithelium and the aleurone, to the starchy endosperm, which has undergone programmed cell death. Numerous a-amylase isoforms have been identified in cereals, but the predominant a-amylase isoform I-1 (AmyI-1) in rice (Oryza sativa) is a unique glycoprotein that bears N-linked oligosaccharide side chains (Hayashi et al., 1990;Terashima et al., 1994). The biosynthesis and secretion of AmyI-1 have been extensively investigated: mRNA translation on endoplasmic reticulum (ER) membrane-bound ribosomes, signal sequence-dependent translocation of the ER, core glycosylation in the ER lumen, vesicular transport to the Golgi apparatus, oligosaccharide modification to the complex type, and exocytosis all proceed according to the canonical secretory mechanism (Palade, 1975;Blobel, 1980;Kornfeld and Kornfeld, 1985).Protein targeting into plastids is an essential cellular event for maintaining plant function and plant life. Plastids, including chloroplasts in green leaves and amyloplasts in starchy cells, contain the genetic machinery required to synthesize their own proteins, although most plastidial proteins are encoded in the nuclear DNA. Nuclear-encoded plastidial...

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“…4 6) α Amylase I 1 encoded by RAmy1A is a glycoprotein bearing typical N linked oligosaccharide chains. 7,8) This isoform is heat stable compared with the other isoforms. The conjugation of an oligosaccharide side chain to polypeptide was thought to be involved in its heat stability.…”

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confidence: 99%

.ALPHA.-Amylase Affects Starch Accumulation in Rice Grains

Asatsuma¹,

Sawada²,

Kitajima³

et al. 2006

J. Appl. Glycosci.

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α Amylases (EC 3.2.1.1) in cereal are polymorphic enzymes. Ten distinct α amylase genes have been cloned and sequenced, 1 3) and more than 20 native α amylase isoforms have been identified and characterized in rice. 4 6) α Amylase I 1 encoded by RAmy1A is a glycoprotein bearing typical N linked oligosaccharide chains. 7,8) This isoform is heat stable compared with the other isoforms. The conjugation of an oligosaccharide side chain to polypeptide was thought to be involved in its heat stability.9,10) In germinating rice seeds, the expression of α amylase I 1 is regulated by gibberellin at both transcriptional and post transcriptional steps. 11,12) The enzyme is synthesized in the scutellar epithelium and the aleurone layer, and subsequently secreted to the starchy endosperm.6) The experimental data obtained by employing the transgenic rice plant with suppressed expression of α amylase I 1 revealed that this isoform plays an important role during seed germination and seedling growth. 13)α Amylase II 4 encoded by RAmy3D (Amy3) is actively expressed in suspension cultured cells derived from the rice embryo. The α amylase II 4 expression is regulated by sugars transcriptionally and post transcriptionally.14 18) At an early stage of germination, α amylase II 4 is a predominant isoform expressed in the coleoptile tissues of rice seed. This isoform is also expressed and secreted from the scutellar epithelium at the early stage of germination and the aleurone layer at the later stage.6) The expression of α amylase II 3 encoded by RAmy3E (Amy8) was detected in germinating seeds and suspension cultured cells derived from the embryo in rice. 3,5,19) The transcription of the α amylase II 3 gene has been reported to be regulated by sugars and hormones through Myb transacting factors. 20) α Amylase II 5 6 encoded by RAmy3B C was also detected in the germinating seeds.5) Similar to the other α amylase isoforms, the expression of α amylase II 5 6 was suggested be regulated by gibberellin and abscisic acid in germinating seeds. 5)As described above, α amylase is a key enzyme for germination and seedling growth of rice seeds. However, we found the typical α amylase isoforms I 1 and II 4 in ripening seeds. We examined the function of α amylase in grain during the ripening period in transgenic rice plants overexpressing the enzyme isoforms. MATERIALS AND METHODS Plant materials.The rice variety (Oryza sativa L. cv. Nipponbare) used in this study was supplied from the Niigata Agricultural Research Institute (Niigata, Japan).Assays. Starch and protein contents were determined as described by Matsukura et al . 21) and Bradford, 22) respectively. α Amylase activity was determined using β limit dextrin as the substrate. β limit dextrin was prepared by hydrolyzing potato starch solution (2% w v in 50 mM acetate buffer, pH 5.3), using crystalline potato β amylase free from α amylase (24 h, 30 C). 0.3% β limit dextrin dissolved in 50 mM acetate buffer (pH 5.3) containing 1 mM CaCl2 served as the substrate. The reaction mixture contain...

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Structure and biosynthesis of the xylose‐containing carbohydrate moiety of rice α‐amylase

Cited by 52 publications

References 42 publications

Distribution of xylosylation and fucosylation in the plant Golgi apparatus

Distribution of xylosylation and fucosylation in the plant Golgi apparatus

The Rice α-Amylase Glycoprotein Is Targeted from the Golgi Apparatus through the Secretory Pathway to the Plastids

.ALPHA.-Amylase Affects Starch Accumulation in Rice Grains

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