A5083759041- Food composition and properties
- Biofuel production and bioconversion
- Enzyme Production and Characterization
- Phytase and its Applications
- Plant Stress Responses and Tolerance
- Photosynthetic Processes and Mechanisms
- Lipid metabolism and biosynthesis
- Microbial Metabolic Engineering and Bioproduction
- Plant nutrient uptake and metabolism
- Rice Cultivation and Yield Improvement
- Microbial Metabolites in Food Biotechnology
- Polysaccharides and Plant Cell Walls
- Genomics and Phylogenetic Studies
- Genetic Mapping and Diversity in Plants and Animals
- Plant biochemistry and biosynthesis
- Bacterial Genetics and Biotechnology
- Enzyme Catalysis and Immobilization
- Crop Yield and Soil Fertility
- Chromosomal and Genetic Variations
- Plant responses to water stress
- Cassava research and cyanide
- Fungal and yeast genetics research
Iowa State University
2013-2023
Unité de Glycobiologie Structurale et Fonctionnelle
2010
Centre National de la Recherche Scientifique
2010
Biopolymères Interactions Assemblages
2009
University of Guelph
2008
Mutations affecting specific starch biosynthetic enzymes commonly have pleiotropic effects on other in the same metabolic pathway. Such genetic evidence indicates functional relationships between components of system, including synthases (SSs), branching (BEs), and debranching enzymes; however, molecular explanation for these interactions is not known. One possibility that SSs, BEs, and/or associate physically with each multisubunit complexes. To test this hypothesis, study sought to...
Abstract Starch biosynthetic enzymes from maize (Zea mays) and wheat (Triticum aestivum) amyloplasts exist in cell extracts high molecular weight complexes; however, the nature of those assemblies remains to be defined. This study tested interdependence starch synthase IIa (SSIIa), SSIII, branching enzyme IIb (SBEIIb), SBEIIa for assembly into multisubunit complexes. Mutations that eliminated any one proteins also prevented others assembling a mass form approximately 670 kD, so SSIIa,...
Sweet corn is one of the most important vegetables in United States and Canada. Here, we present a de novo assembly sweet inbred line Ia453 with mutated shrunken2-reference allele (Ia453-sh2). This mutation accumulates more sugar commercial hybrids developed for processing fresh markets. The ten pseudochromosomes cover 92% total 99% estimated genome size, scaffold N50 222.2 Mb. reference completely assembles large structural variation that created mutant sh2-R allele. Furthermore,...
Abstract Functions of isoamylase-type starch-debranching enzyme (ISA) proteins and complexes in maize (Zea mays) endosperm were characterized. Wild-type contained three high molecular mass ISA resolved by gel permeation chromatography native-polyacrylamide electrophoresis. Two approximately 400 kD both ISA1 ISA2, an 300-kD complex but not ISA2. Novel mutations sugary1 (su1) isa2, coding for respectively, used to develop one line with homomer lacking heteromeric a second form ISA1/ISA2...
Abstract This study characterized genetic interactions between the maize (Zea mays) genes dull1 (du1), encoding starch synthase III (SSIII), and isa2, a noncatalytic subunit of heteromeric isoamylase-type starch-debranching enzyme (ISA1/ISA2 heteromer). Mutants lacking ISA2 still possess ISA1 homomeric enzyme. Eight du1- mutations were characterized, structural changes in amylopectin resulting from each measured. In every instance, same complex pattern alterations discontinuous spans chain...
The maize (Zea mays) opaque5 (o5) locus was shown to encode the monogalactosyldiacylglycerol synthase MGD1. Null and point mutations of o5 that affect vitreous nature mature endosperm engendered an allelic series lines with stepwise reductions in gene function. C(18:3)/C(18:2) galactolipid abundance seedling leaves reduced proportionally, without significant effects on total content. This alteration polar lipid composition disrupted organization thylakoid membranes into granal stacks. Total...
This study assessed the impact on starch metabolism in Arabidopsis leaves of simultaneously eliminating multiple soluble synthases (SS) from among SS1, SS2, and SS3. Double mutant ss1- ss2- or ss3- lines were generated using confirmed null mutations. These compared to wild type, each single mutant, triple grown standardized environments. plants developed similarly although they accumulated less leaf both short-day long-day diurnal cycles. Despite reduced levels double mutants, containing...
Abstract ADP-glucose pyrophosphorylase (AGPase) provides the nucleotide sugar and thus constitutes first step in starch biosynthesis. The majority of cereal endosperm AGPase is located cytosol with a minor portion amyloplasts, contrast to its strictly plastidial location other species tissues. To investigate potential functions maize (Zea mays) endosperm, six genes encoding large or small subunits were characterized for gene expression as well subcellular biochemical activity encoded...
Cereal yields decrease when grain fill proceeds under conditions of prolonged, moderately elevated temperatures. Endosperm-endogenous processes alter both rate and duration dry weight gain, but underlying mechanisms remain unclear. Heat effects could be mediated by either abnormal, premature cessation storage compound deposition or accelerated implementation normal development. This study used controlled environments to isolate temperature as the sole environmental variable during Zea mays...
The ascomycete Saccharomyces cerevisiae exhibits alternative vegetative growth states referred to as the yeast form and filamentous form, it switches between two morphologies depending on specific environmental signals. To identify molecules involved in control of morphologic differentiation, this study characterized mutant S. strains that exhibit absence normal external A amino acid substitution cyclin-dependent protein kinase Cdc28 was found cause constitutive expression most...
Maize opaque2 (o2) mutations are beneficial for endosperm nutritional quality but cause negative pleiotropic effects reasons that not fully understood. Direct targets of the bZIP transcriptional regulator encoded by o2 include pdk1 and pdk2 specify pyruvate phosphate dikinase (PPDK). This enzyme reversibly converts AMP, pyrophosphate, phosphoenolpyruvate to ATP, orthophosphate, provides diverse functions in plants. study addressed PPDK function maize starchy where it is highly abundant...
Escherichia coli was engineered for the production of even- and odd-chain fatty acids (FAs) by fermentation. Co-production thiolase, hydroxybutyryl-CoA dehydrogenase, crotonase trans -enoyl-CoA reductase from a synthetic operon allowed butyrate, hexanoate octanoate. Elimination native fermentation pathways genetic deletion (Δ ldhA , Δ adhE ackA pta frdC ) helped eliminate undesired by-products increase product yields. Initial butyrate rates were high (0.7 g l −1 h but quickly levelled off...
Endosperm starch synthesis is a primary determinant of grain yield and sensitive to high-temperature stress. The maize chloroplast-localized 6-phosphogluconate dehydrogenase (6PGDH), PGD3, critical for endosperm accumulation. Maize also has two cytosolic isozymes, PGD1 PGD2, that are not required kernel development. We found PGD2 isozymes have heat-stable activity, while amyloplast-localized PGD3 activity labile under heat stress conditions. targeted 6PGDH amyloplasts by fusing the Waxy1...
Isoamylase-type starch debranching enzymes (ISA) play important roles in biosynthesis chloroplast-containing organisms, as shown by the strict conservation of both catalytically active ISA1 and noncatalytic homolog ISA2. Functional distinctions exist between species, although they are not understood yet. Numerous plant tissues require ISA2 for normal biosynthesis, whereas monocot endosperm leaf exhibit nearly metabolism without This study took vivo vitro approaches to determine whether...
Conserved isoamylase-type starch debranching enzymes (ISAs), including the catalytic ISA1 and noncatalytic ISA2, are major biosynthesis determinants. Arabidopsis thaliana leaves require ISA2 for physiological function, whereas endosperm is near normal with only ISA1. ISA functions were characterized in maize (Zea mays) to determine whether species-specific distinctions primary structure, or metabolic differences tissues, responsible differing requirement. Genetic methods provided lines...
The opaque-2 (o2) mutation of maize increases lysine content, but the low seed density and soft texture this type mutant are undesirable. Lines with modifiers kernel phenotype (mo2) called “Quality Protein Maize” (QPM) have high phenotypes similar to normal maize. Prior research indicated that formation vitreous endosperm in QPM might involve changes starch granule structure. In study, we focused on analysis two biosynthetic enzymes may influence vitreousness. Analysis recombinant inbred...
Starch synthase (SS) (ADP-glucose:1,4-α-D-glucan 4-α-D-glucosyltransferase) elongates α-(1→4)-linked linear glucans within plastids to generate the storage polymers that constitute starch granules. Multiple SS classes are conserved throughout plant kingdom, indicating each provides a unique function responsible for evolutionary selection. Evidence has been presented arguing addition of glucosyl units from ADPglucose donor either reducing end or non-reducing acceptor substrate, although until...
Abstract Endosperm starch synthesis is a primary determinant of grain yield and sensitive to high temperature stress. The maize chloroplast-localized 6-phosphogluconate dehydrogenase (6PGDH), PGD3, critical for endosperm accumulation. Maize also has two cytosolic isozymes, PGD1 PGD2 that are not required kernel development. We found isozymes have heat stable activity, while amyloplast-localized PGD3 activity labile under stress conditions. targeted heat-stable 6PGDH amyloplasts by fusing the...
Molecular mechanisms that distinguish the synthesis of semi-crystalline α-glucan polymers found in plant starch granules from water-soluble by nonplant species are not well understood. To address this, biosynthetic enzymes maize (Zea mays L.) endosperm were isolated a reconstituted environment using yeast (Saccharomyces cerevisiae) as test bed. Ninety strains constructed containing unique combinations 11 synthetic transcription units specifying synthase (SS), phosphorylase (PHO), branching...
Maize seeds provide a major component of the calories in human diet, are critical as feed source animal agriculture, and an important biorenewable raw materials. Endosperm tissue accounts for approximately 80% seed weight, is site where carbohydrate protein storage end products produced this net anabolic system. Sucrose supplied from photosynthetic tissues maternal plant transported to growing it divided between catabolic pathways that generate ATP biosynthetic processes utilize starch...