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[PMID]:28726249
[Au] Autor:Xiao Q; Wang Y; Du J; Li H; Wei B; Wang Y; Li Y; Yu G; Liu H; Zhang J; Liu Y; Hu Y; Huang Y
[Ad] Endereço:College of Agronomy, Sichuan Agricultural University, Chengdu, China.
[Ti] Título:ZmMYB14 is an important transcription factor involved in the regulation of the activity of the ZmBT1 promoter in starch biosynthesis in maize.
[So] Source:FEBS J;284(18):3079-3099, 2017 Sep.
[Is] ISSN:1742-4658
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:The biosynthesis of starch is a complex process that depends on the regulatory mechanisms of different functional enzymes, and transcriptional regulation plays an important role in this process. Brittle 1, encoded by BT1, is a transporter of adenosine diphosphate-glucose, which plays an important role in the biosynthesis of starch in the endosperm of cereals. Here, we report that the promoter (pZmBT1) of the maize BT1 homolog, ZmBT1, contains an MBSI site (TAACTG), which is important for its activity. Moreover, high expression level of the gene for ZmMYB14 transcription factor was observed in the maize endosperm; its expression pattern was similar to those of the starch synthesis-related genes in maize seeds. ZmMYB14 is a typical 2R-MYB transcription factor localized in the nucleus and possessed transcriptional activation activity. ZmMYB14 could bind to the region of pZmBT1 from -280 to -151 bp and promote its activity through the TAACTG site. It was also observed to promote the activity of pZmSh2, pZmBt2, pZmGBSSI, pZmSSI, and pZmSBE1 in the maize endosperm in transient gene overexpression assays. Furthermore, ZmMYB14 was also shown to bind directly to the promoters of six starch-synthesizing genes, ZmGBSSI, ZmSSI, ZmSSIIa, ZmSBE1, ZmISA1, and ZmISA2 in yeast. These findings indicate that ZmMYB14 functions as a key regulator of ZmBT1 and is closely related to the biosynthesis of starch. Our results provide crucial information related to the regulation of starch biosynthesis in maize and would be helpful in devising strategies for modulating starch production in maize endosperm.
[Mh] Termos MeSH primário: Proteínas de Transporte/genética
Regulação da Expressão Gênica de Plantas
Proteínas de Plantas/genética
Amido/biossíntese
Fatores de Transcrição/genética
Zea mays/genética
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Sítios de Ligação
Proteínas de Transporte/metabolismo
Endosperma/genética
Endosperma/crescimento & desenvolvimento
Endosperma/metabolismo
Ontologia Genética
Glucosiltransferases/genética
Glucosiltransferases/metabolismo
Isoamilase/genética
Isoamilase/metabolismo
Isoenzimas/genética
Isoenzimas/metabolismo
Anotação de Sequência Molecular
Proteínas de Plantas/metabolismo
Plantas Geneticamente Modificadas
Regiões Promotoras Genéticas
Ligação Proteica
Sintase do Amido/genética
Sintase do Amido/metabolismo
Fatores de Transcrição/metabolismo
Ativação Transcricional
Zea mays/crescimento & desenvolvimento
Zea mays/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Carrier Proteins); 0 (Isoenzymes); 0 (Plant Proteins); 0 (Transcription Factors); 9005-25-8 (Starch); EC 2.4.1.- (Glucosyltransferases); EC 2.4.1.- (granule-bound starch synthase I); EC 2.4.1.21 (Starch Synthase); EC 3.2.1.68 (Isoamylase)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171004
[Lr] Data última revisão:
171004
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170721
[St] Status:MEDLINE
[do] DOI:10.1111/febs.14179


  2 / 420 MEDLINE  
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[PMID]:28330563
[Au] Autor:Itoh Y; Crofts N; Abe M; Hosaka Y; Fujita N
[Ad] Endereço:Department of Biological Production, Akita Prefectural University, Akita 010-0195, Japan.
[Ti] Título:Characterization of the endosperm starch and the pleiotropic effects of biosynthetic enzymes on their properties in novel mutant rice lines with high resistant starch and amylose content.
[So] Source:Plant Sci;258:52-60, 2017 May.
[Is] ISSN:1873-2259
[Cp] País de publicação:Ireland
[La] Idioma:eng
[Ab] Resumo:Resistant starch (RS) is beneficial to human health. In order to reduce the current prevalence of diabetes and obesity, several transgenic and mutant crops containing high RS content are being developed. RS content of steamed rice with starch-branching enzyme (BE)IIb-deficient mutant endosperms is considerably high. To understand the mechanisms of RS synthesis and to increase RS content, we developed novel mutant rice lines by introducing the gene encoding starch synthase (SS)IIa and/or granule-bound starch synthase (GBSS)I from an indica rice cultivar into a japonica rice-based BEIIb-deficient mutant line, be2b. Introduction of SSIIa from an indica rice cultivar produced higher levels of amylopectin chains with degree of polymerization (DP) 11-18 than those in be2b; the extent of the change was slight due to the shortage of donor chains for SSIIa (DP 6-12) owing to BEIIb deficiency. The introduction of GBSSI from an indica rice cultivar significantly increased amylose content (by approximately 10%) in the endosperm starch. RS content of the new mutant lines was the same as or slightly higher than that of the be2b parent line. The relationship linking starch structure, RS content, and starch biosynthetic enzymes in the new mutant lines has also been discussed.
[Mh] Termos MeSH primário: Amilose/metabolismo
Endosperma/química
Oryza/metabolismo
Amido/metabolismo
[Mh] Termos MeSH secundário: Amilopectina/análise
Amilopectina/metabolismo
Amilose/análise
Endosperma/metabolismo
Oryza/química
Oryza/enzimologia
Oryza/genética
Plantas Geneticamente Modificadas/química
Plantas Geneticamente Modificadas/enzimologia
Plantas Geneticamente Modificadas/genética
Plantas Geneticamente Modificadas/metabolismo
Amido/análise
Amido/biossíntese
Amido/química
Sintase do Amido/genética
Sintase do Amido/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
9005-25-8 (Starch); 9005-82-7 (Amylose); 9037-22-3 (Amylopectin); EC 2.4.1.21 (Starch Synthase)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170519
[Lr] Data última revisão:
170519
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170324
[St] Status:MEDLINE


  3 / 420 MEDLINE  
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[PMID]:28314934
[Au] Autor:Zhang LL; Chen H; Luo M; Zhang XW; Deng M; Ma J; Qi PF; Wang JR; Chen GY; Liu YX; Pu ZE; Li W; Lan XJ; Wei YM; Zheng YL; Jiang QT
[Ad] Endereço:Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
[Ti] Título:Transposon insertion resulted in the silencing of Wx-B1n in Chinese wheat landraces.
[So] Source:Theor Appl Genet;130(6):1321-1330, 2017 Jun.
[Is] ISSN:1432-2242
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:KEY MESSAGE: A novel Wx-B1 allele was characterized; a transposon insertion resulted in the loss of its function, which is different from the previously reported gene silencing mechanisms at the Wx-B1 locus. The waxy protein composition of 53 Chinese wheat landraces was analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis; of these, 10 did not show the expression of Wx-A1 (four accession) or Wx-B1 (six accessions) protein. The results of molecular marker detection revealed that the Wx-B1 allele (Wx-B1n) showed normal expression, inconsistent with the findings of SDS-PAGE for the Xiaobaipi accession. Further cloning of the 9160-bp region covering the Wx-B1 coding region and 3'-downstream region revealed that a 2178-bp transposon fragment had been inserted at 2462 bp within the tenth exon of Wx-B1n ORF, leading to the absence of Wx-B1 protein. Sequence analysis indicated that the insertion possessed the structural features of invert repeat and target repeat elements, we deduced that it was a transposon. Further PCR analysis revealed that this fragment had moved, but not copied itself, from 3B chromosome to the current location in Wx-B1n. Therefore, the reason for the inactivation of Wx-B1n was considerably different from those for the inactivation of Wx-B1b, Wx-B1k, and Wx-B1m; to our knowledge, this kind of structural mutation has never been reported in Wx-B1 alleles. This novel allele is interesting, because it was not associated with the deletion of other quality-related genes included in the 67 kb region lost with the common null allele Wx-B1b. The null Wx-B1n might be useful for investigating gene inactivation and expression as well as for enriching the genetic resource pool for the modification of the amylose/amylopectin ratio, thereby improving wheat quality.
[Mh] Termos MeSH primário: Elementos de DNA Transponíveis
Inativação Gênica
Sintase do Amido/genética
Triticum/genética
[Mh] Termos MeSH secundário: Alelos
Sequência de Aminoácidos
Sequência de Bases
Passeio de Cromossomo
Clonagem Molecular
Genes de Plantas
Mutagênese Insercional
Fases de Leitura Aberta
Proteínas de Plantas/genética
Triticum/enzimologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (DNA Transposable Elements); 0 (Plant Proteins); EC 2.4.1.21 (Starch Synthase)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170917
[Lr] Data última revisão:
170917
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170319
[St] Status:MEDLINE
[do] DOI:10.1007/s00122-017-2878-4


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[PMID]:28241110
[Au] Autor:Zhang C; Chen S; Ren X; Lu Y; Liu D; Cai X; Li Q; Gao J; Liu Q
[Ad] Endereço:Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University , Yangzhou 225009, China.
[Ti] Título:Molecular Structure and Physicochemical Properties of Starches from Rice with Different Amylose Contents Resulting from Modification of OsGBSSI Activity.
[So] Source:J Agric Food Chem;65(10):2222-2232, 2017 Mar 15.
[Is] ISSN:1520-5118
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:OsGBSSI, encoded by the Waxy (Wx) gene, is the key enzyme in the synthesis of amylose chains. Transgenic rice lines with various GBSSI activities were previously developed via site-directed mutagenesis of the Wx gene in the glutinous cultivar Guanglingxiangnuo (GLXN). In this study, grain morphology, molecular structure, and physicochemical properties were investigated in four transgenic lines with modified OsGBSSI activity and differences in amylose content. A milky opaque appearance was observed in low- and non-amylose rice grains due to air spaces in the starch granules. Gel permeation chromatography (GPC) and high-performance anion-exchange chromatography (HPAEC) analyses showed that although OsGBSSI can synthesize intermediate and extra-long amylopectin chains, it is mainly responsible for the longer amylose chains. Amylose content was positively correlated with trough viscosity, final viscosity, setback viscosity, pasting time, pasting temperature, and gelatinization temperature and negatively with gel consistency, breakdown viscosity, gelatinization enthalpy, and crystallinity. Overall, the findings suggest that OsGBSSI may be also involved in amylopectin biosynthesis, in turn affecting grain appearance, thermal and pasting properties, and the crystalline structure of starches in the rice endosperm.
[Mh] Termos MeSH primário: Amilose/análise
Oryza/enzimologia
Proteínas de Plantas/metabolismo
Sintase do Amido/metabolismo
Amido/química
[Mh] Termos MeSH secundário: Amilose/metabolismo
Oryza/química
Oryza/genética
Oryza/metabolismo
Proteínas de Plantas/genética
Amido/metabolismo
Sintase do Amido/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Plant Proteins); 9005-25-8 (Starch); 9005-82-7 (Amylose); EC 2.4.1.- (granule-bound starch synthase I); EC 2.4.1.21 (Starch Synthase)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170526
[Lr] Data última revisão:
170526
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170228
[St] Status:MEDLINE
[do] DOI:10.1021/acs.jafc.6b05448


  5 / 420 MEDLINE  
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[PMID]:28088172
[Au] Autor:Raja RB; Agasimani S; Jaiswal S; Thiruvengadam V; Sabariappan R; Chibbar RN; Ram SG
[Ad] Endereço:Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, 641 003, Tamil Nadu, India.
[Ti] Título:EcoTILLING by sequencing reveals polymorphisms in genes encoding starch synthases that are associated with low glycemic response in rice.
[So] Source:BMC Plant Biol;17(1):13, 2017 Jan 14.
[Is] ISSN:1471-2229
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: Glycemic response, a trait that is tedious to be assayed in cereal staples, has been identified as a factor correlated with alarmingly increasing prevalence of Type II diabetes. Reverse genetics based discovery of allelic variants associated with this nutritional trait gains significance as they can provide scope for genetic improvement of this factor which is otherwise difficult to target through routine screening methods. RESULTS: Through EcoTILLING by sequencing in 512 rice accessions, we report the discovery of six deleterious variants in the genes with potential to increase Resistant Starch (RS) and reduce Hydrolysis Index (HI) of starch. By deconvolution of the variant harbouring EcoTILLING DNA pools, we discovered accessions with a minimum of one to a maximum of three deleterious allelic variants in the candidate genes. CONCLUSIONS: Through biochemical assays, we confirmed the potential role of the discovered alleles alone or in combinations in increasing RS the key factor for reduction in glycemic response.
[Mh] Termos MeSH primário: Oryza/enzimologia
Proteínas de Plantas/genética
Polimorfismo Genético
Sintase do Amido/genética
Amido/metabolismo
[Mh] Termos MeSH secundário: Alelos
Mutação
Oryza/classificação
Oryza/genética
Proteínas de Plantas/metabolismo
Análise de Sequência de DNA
Sintase do Amido/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Plant Proteins); 9005-25-8 (Starch); EC 2.4.1.21 (Starch Synthase)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171023
[Lr] Data última revisão:
171023
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170116
[St] Status:MEDLINE
[do] DOI:10.1186/s12870-016-0968-0


  6 / 420 MEDLINE  
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[PMID]:28003125
[Au] Autor:Barchiesi J; Hedin N; Iglesias AA; Gomez-Casati DF; Ballicora MA; Busi MV
[Ad] Endereço:Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario, Suipacha 531, Rosario, 2000, Argentina.
[Ti] Título:Identification of a novel starch synthase III from the picoalgae Ostreococcus tauri.
[So] Source:Biochimie;133:37-44, 2017 Feb.
[Is] ISSN:1638-6183
[Cp] País de publicação:France
[La] Idioma:eng
[Ab] Resumo:Hydrosoluble glycogen is the major energy storage compound in bacteria, archaea, fungi, and animal cells. In contrast, photosynthetic eukaryotes have evolved to build a highly organized semicrystalline granule of starch. Several enzymes are involved in polysaccharide synthesis, among which glycogen or starch synthase catalyze the elongation of the α-1,4-glucan chain. Ostreococcus tauri, accumulates a single starch granule and contains three starch synthase III (SSIII) isoforms, known as OsttaSSIII-A, OsttaSSIII-B and OsttaSSIII-C. After amino acids sequence analysis we found that OsttaSSIII-C lacks starch-binding domains, being 49% identical to the catalytic region of the SSIII from Arabidopsis thaliana and 32% identical to the entire Escherichia coli glycogen synthase. The recombinant, highly purified OsttaSSIII-C exhibited preference to use as a primer branched glycans (such as rabbit muscle glycogen and amylopectin), rather than amylose. Also, the enzyme displayed a high affinity toward ADP-glucose. We found a marked conservation of the amino acids located in the catalytic site, and specifically determined the role of residues R270, K275 and E352 by site-directed mutagenesis. Results show that these residues are important for OsttaSSIII-C activity, suggesting a strong similarity between the active site of the O. tauri SSIII-C isoform and other bacterial glycogen synthases.
[Mh] Termos MeSH primário: Clorófitas/enzimologia
Glicogênio Sintase/química
Glicogênio/metabolismo
Sintase do Amido/química
[Mh] Termos MeSH secundário: Amilose/química
Animais
Arabidopsis/enzimologia
Catálise
Domínio Catalítico
Escherichia coli/enzimologia
Glucose/metabolismo
Glicogênio/química
Glicogênio Sintase/genética
Glicogênio Sintase/metabolismo
Polissacarídeos/metabolismo
Isoformas de Proteínas/química
Isoformas de Proteínas/genética
Isoformas de Proteínas/metabolismo
Coelhos
Análise de Sequência de Proteína
Sintase do Amido/genética
Sintase do Amido/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Polysaccharides); 0 (Protein Isoforms); 9005-79-2 (Glycogen); 9005-82-7 (Amylose); EC 2.4.1.11 (Glycogen Synthase); EC 2.4.1.21 (Starch Synthase); IY9XDZ35W2 (Glucose)
[Em] Mês de entrada:1701
[Cu] Atualização por classe:170130
[Lr] Data última revisão:
170130
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161223
[St] Status:MEDLINE


  7 / 420 MEDLINE  
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[PMID]:27513992
[Au] Autor:Bahuguna RN; Solis CA; Shi W; Jagadish KS
[Ad] Endereço:Crop and Environmental Sciences Division, International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines.
[Ti] Título:Post-flowering night respiration and altered sink activity account for high night temperature-induced grain yield and quality loss in rice (Oryza sativa L.).
[So] Source:Physiol Plant;159(1):59-73, 2017 Jan.
[Is] ISSN:1399-3054
[Cp] País de publicação:Denmark
[La] Idioma:eng
[Ab] Resumo:High night temperature (HNT) is a major constraint to sustaining global rice production under future climate. Physiological and biochemical mechanisms were elucidated for HNT-induced grain yield and quality loss in rice. Contrasting rice cultivars (N22, tolerant; Gharib, susceptible; IR64, high yielding with superior grain quality) were tested under control (23°C) and HNT (29°C) using unique field-based tents from panicle initiation till physiological maturity. HNT affected 1000 grain weight, grain yield, grain chalk and amylose content in Gharib and IR64. HNT increased night respiration (Rn) accounted for higher carbon losses during post-flowering phase. Gharib and IR64 recorded 16 and 9% yield reduction with a 63 and 35% increase in average post-flowering Rn under HNT, respectively. HNT altered sugar accumulation in the rachis and spikelets across the cultivars with Gharib and IR64 recording higher sugar accumulation in the rachis. HNT reduced panicle starch content in Gharib (22%) and IR64 (11%) at physiological maturity, but not in the tolerant N22. At the enzymatic level, HNT reduced sink strength with lower cell wall invertase and sucrose synthase activity in Gharib and IR64, which affected starch accumulation in the developing grain, thereby reducing grain weight and quality. Interestingly, N22 recorded lower Rn-mediated carbon losses and minimum impact on sink strength under HNT. Mechanistic responses identified will facilitate crop models to precisely estimate HNT-induced damage under future warming scenarios.
[Mh] Termos MeSH primário: Carbono/metabolismo
Regulação da Expressão Gênica de Plantas
Oryza/metabolismo
[Mh] Termos MeSH secundário: Biomassa
Respiração Celular
Grãos Comestíveis/crescimento & desenvolvimento
Grãos Comestíveis/metabolismo
Flores/crescimento & desenvolvimento
Flores/metabolismo
Glucosiltransferases/metabolismo
Temperatura Alta
Oryza/crescimento & desenvolvimento
Proteínas de Plantas/metabolismo
Amido/metabolismo
Sintase do Amido/metabolismo
beta-Frutofuranosidase/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Plant Proteins); 7440-44-0 (Carbon); 9005-25-8 (Starch); EC 2.4.1.- (Glucosyltransferases); EC 2.4.1.13 (sucrose synthase); EC 2.4.1.21 (Starch Synthase); EC 3.2.1.26 (beta-Fructofuranosidase)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170306
[Lr] Data última revisão:
170306
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160812
[St] Status:MEDLINE
[do] DOI:10.1111/ppl.12485


  8 / 420 MEDLINE  
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[PMID]:27312246
[Au] Autor:Xiang X; Kang C; Xu S; Yang B
[Ad] Endereço:Laboratory of Plant Molecular Genetics and Breeding, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang, 621010, China.
[Ti] Título:Combined effects of Wx and SSIIa haplotypes on rice starch physicochemical properties.
[So] Source:J Sci Food Agric;97(4):1229-1234, 2017 Mar.
[Is] ISSN:1097-0010
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: Wx and SSIIa are central genes for determining starch physicochemical properties and rice endosperm starch is composed of linear amylose, which is entirely synthesized by granule bound starch synthase I (GBSSI, encoded by Wx) and branched amylopectin. In the present study, different haplotypes of rice were examined to investigate the combined effects of pivotal genes in the metabolic chain of starch, Wx and SSIIa. RESULTS: Wx haplotypes differed in terms of apparent amylose content (AAC) and gel consistency (GC). The I-3 [haplotype I (Int1T/Ex10C) of Wx and haplotype 3 (A-G-TT) of SSIIa] and the I-4 combinations of rice had better eating and cooking qualities (ECQs) with lower AAC, lower gelatinization temperature (GT) and softer GC. CONCLUSION: The characteristic parameters of Rapid Visco-analyser (RVA) could distinguish differences in AAC and GC but not GT. The I-3 and I-4 haplotype combinations of Wx and SSIIa represent key targets for the production of rice with better ECQs. © 2016 Society of Chemical Industry.
[Mh] Termos MeSH primário: Amilose/biossíntese
Endosperma/metabolismo
Genes de Plantas
Haplótipos
Oryza/genética
Proteínas de Plantas/genética
Sintase do Amido/genética
[Mh] Termos MeSH secundário: Amilopectina/metabolismo
Culinária
Grãos Comestíveis/metabolismo
Grãos Comestíveis/normas
Géis
Seres Humanos
Oryza/metabolismo
Proteínas de Plantas/metabolismo
Polimorfismo de Nucleotídeo Único
Amido/metabolismo
Amido/normas
Sintase do Amido/metabolismo
Temperatura Ambiente
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Gels); 0 (Plant Proteins); 122933-70-4 (waxy protein, plant); 9005-25-8 (Starch); 9005-82-7 (Amylose); 9037-22-3 (Amylopectin); EC 2.4.1.- (granule-bound starch synthase I); EC 2.4.1.21 (Starch Synthase)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170630
[Lr] Data última revisão:
170630
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160618
[St] Status:MEDLINE
[do] DOI:10.1002/jsfa.7854


  9 / 420 MEDLINE  
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[PMID]:27733678
[Au] Autor:Larson ME; Falconer DJ; Myers AM; Barb AW
[Ad] Endereço:From the Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011.
[Ti] Título:Direct Characterization of the Maize Starch Synthase IIa Product Shows Maltodextrin Elongation Occurs at the Non-reducing End.
[So] Source:J Biol Chem;291(48):24951-24960, 2016 Nov 25.
[Is] ISSN:1083-351X
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:A comprehensive description of starch biosynthesis and granule assembly remains undefined despite the central nature of starch as an energy storage molecule in plants and as a fundamental calorie source for many animals. Multiple theories regarding the starch synthase (SS)-catalyzed assembly of (α1-4)-linked d-glucose molecules into maltodextrins generally agree that elongation occurs at the non-reducing terminus based on the degradation of radiolabeled maltodextrins, although recent reports challenge this hypothesis. Surprisingly, a direct analysis of the SS catalytic product has not been reported, to our knowledge. We expressed and characterized recombinant Zea mays SSIIa and prepared pure ADP-[ C ]glucose in a one-pot enzymatic synthesis to address the polarity of maltodextrin chain elongation. We synthesized maltoheptaose (degree of polymerization 7) using ADP-[ C ]glucose, maltohexaose (degree of polymerization 6), and SSIIa. Product analysis by ESI-MS revealed that the [ C ]glucose unit was added to the non-reducing end of the growing chain, and SSIIa demonstrated a >7,850-fold preference for addition to the non-reducing end versus the reducing end. Independent analysis of [ C ]glucose added to maltohexaose by SSIIa using solution NMR spectroscopy confirmed the polarity of maltodextrin chain elongation.
[Mh] Termos MeSH primário: Proteínas de Plantas/química
Polissacarídeos/química
Sintase do Amido/química
Zea mays/enzimologia
[Mh] Termos MeSH secundário: Glucose/química
Glucose/metabolismo
Ressonância Magnética Nuclear Biomolecular
Oligossacarídeos/química
Oligossacarídeos/metabolismo
Proteínas de Plantas/metabolismo
Polissacarídeos/biossíntese
Sintase do Amido/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Oligosaccharides); 0 (Plant Proteins); 0 (Polysaccharides); 34620-77-4 (maltohexaose); 7CVR7L4A2D (maltodextrin); EC 2.4.1.- (starch synthase II); EC 2.4.1.21 (Starch Synthase); IY9XDZ35W2 (Glucose)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:171126
[Lr] Data última revisão:
171126
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161014
[St] Status:MEDLINE


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[PMID]:27523327
[Au] Autor:Zhu F; Bertoft E; Li G
[Ad] Endereço:School of Chemical Sciences, University of Auckland , Private Bag 92019, Auckland 1142, New Zealand.
[Ti] Título:Morphological, Thermal, and Rheological Properties of Starches from Maize Mutants Deficient in Starch Synthase III.
[So] Source:J Agric Food Chem;64(34):6539-45, 2016 Aug 31.
[Is] ISSN:1520-5118
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Morphological, thermal, and rheological properties of starches from maize mutants deficient in starch synthase III (SSIII) with a common genetic background (W64A) were studied and compared with the wild type. SSIII deficiency reduced granule size of the starches from 16.7 to ∼11 µm (volume-weighted mean). Thermal analysis showed that SSIII deficiency decreased the enthalpy change of starch during gelatinization. Steady shear analysis showed that SSIII deficiency decreased the consistency coefficient and yield stress during steady shearing, whereas additional deficiency in granule-bound starch synthase (GBSS) increased these values. Dynamic oscillatory analysis showed that SSIII deficiency decreased G' at 90 °C during heating and increased it when the paste was cooled to 25 °C at 40 Hz during a frequency sweep. Additional GBSS deficiency further decreased the G'. Structural and compositional bases responsible for these changes in physical properties of the starches are discussed. This study highlighted the relationship between SSIII and some physicochemical properties of maize starch.
[Mh] Termos MeSH primário: Proteínas de Plantas/genética
Sintase do Amido/genética
Amido/química
Zea mays/metabolismo
[Mh] Termos MeSH secundário: Temperatura Alta
Mutação
Proteínas de Plantas/metabolismo
Reologia
Amido/metabolismo
Sintase do Amido/metabolismo
Zea mays/química
Zea mays/enzimologia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Plant Proteins); 9005-25-8 (Starch); EC 2.4.1.21 (Starch Synthase)
[Em] Mês de entrada:1704
[Cu] Atualização por classe:170413
[Lr] Data última revisão:
170413
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160816
[St] Status:MEDLINE
[do] DOI:10.1021/acs.jafc.6b01265



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