BIOSYNTHESIS AND DEGRADATION OF STARCH IN HIGHER PLANTS

2020 ◽  
Author(s):  
Lungwani Muungo
Keyword(s):  
Higher Plants ◽  
Starch Biosynthesis ◽  
Metabolizing Enzymes ◽  
Transitory Starch ◽  
Leaf Tissues ◽  
Cellular Compartments

Numerous reviews on starch biosynthesis and degradation have appeared inthe 1980s (4, 23, 39, 40, 51, 73, 100, 101, 124, 125). Here we updateestablished concepts and emphasize three topics that we consider to now meritreexamination: the significance of enzyme multiplicity, a comparison ofdegradation of reserve and transitory starch, and the localization of starchdegrading enzymes in starch-free cellular compartments of leaf tissues. Westress the cell physiological aspects of starch metabolizing enzymes.

scholarly journals Molecular Functions and Pathways of Plastidial Starch Phosphorylase (PHO1) in Starch Metabolism: Current and Future Perspectives

2021 ◽  
Vol 22 (19) ◽  
pp. 10450
Author(s):  
Noman Shoaib ◽  
Lun Liu ◽  
Asif Ali ◽  
Nishbah Mughal ◽  
Guowu Yu ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Molecular Mechanisms ◽  
Higher Plants ◽  
Crop Improvement ◽  
Starch Biosynthesis ◽  
Starch Metabolism ◽  
Protein Protein Interactions ◽  
Starch Phosphorylase ◽  
Integral Role

Starch phosphorylase is a member of the GT35-glycogen-phosphorylase superfamily. Glycogen phosphorylases have been researched in animals thoroughly when compared to plants. Genetic evidence signifies the integral role of plastidial starch phosphorylase (PHO1) in starch biosynthesis in model plants. The counterpart of PHO1 is PHO2, which specifically resides in cytosol and is reported to lack L80 peptide in the middle region of proteins as seen in animal and maltodextrin forms of phosphorylases. The function of this extra peptide varies among species and ranges from the substrate of proteasomes to modulate the degradation of PHO1 in Solanum tuberosum to a non-significant effect on biochemical activity in Oryza sativa and Hordeum vulgare. Various regulatory functions, e.g., phosphorylation, protein–protein interactions, and redox modulation, have been reported to affect the starch phosphorylase functions in higher plants. This review outlines the current findings on the regulation of starch phosphorylase genes and proteins with their possible role in the starch biosynthesis pathway. We highlight the gaps in present studies and elaborate on the molecular mechanisms of phosphorylase in starch metabolism. Moreover, we explore the possible role of PHO1 in crop improvement.

Sucrose Synthase Controls Both Intracellular ADP Glucose Levels and Transitory Starch Biosynthesis in Source Leaves

2005 ◽  
Vol 46 (8) ◽  
pp. 1366-1376 ◽  
Author(s):  
Francisco José Muñoz ◽  
Edurne Baroja-Fernández ◽  
María Teresa Morán-Zorzano ◽  
Alejandro Miguel Viale ◽  
Ed Etxeberria ◽  
...  
Keyword(s):  
Sucrose Synthase ◽  
Starch Biosynthesis ◽  
Glucose Levels ◽  
Transitory Starch

scholarly journals Elucidation of sub-cellular H2S metabolism in Solanum lycopersicum L. and its assessment under development and biotic stress

2021 ◽  
Author(s):  
Aksar Ali Chowdhary ◽  
Sonal Mishra ◽  
Vikram Singh ◽  
Vikas Srivastava
Keyword(s):  
Solanum Lycopersicum ◽  
Higher Plants ◽  
Preliminary Investigation ◽  
Biotic Stresses ◽  
Signalling Molecules ◽  
Solanum Lycopersicum L ◽  
Physiological Processes ◽  
Signalling Molecule ◽  
Cellular Compartments ◽  
Fundamental Requirement

AbstractThe signalling molecules serve as a fundamental requirement in plants and respond to various internal and external cues. Among several signalling molecules, the significance of gasotransmitters has been realized in several plant developmental and environmental constraints. The hydrogen sulfide (H2S) is a novel signalling molecule in higher plants and is involved in several physiological processes right from seed germination to flowering and fruit ripening. Moreover, H2S also assist plants in managing biotic and abiotic stresses, therefore serves as one of the imperative choice of chemical priming. Yet, the metabolism of H2S is not much explored and only appraisal study is made till date from Arabidopsis thaliana. Therefore, the present investigation explored the elucidation of H2S metabolism in crop plant Solanum lycopersicum L. Through in silico investigations the study demonstrated the participation of 29 proteins involved in H2S metabolism, which are mainly localized in cytosol, chloroplast, and mitochondria. Additionally, the relevant protein-protein interactomes were also inferred for sub-cellular compartments and expression data were explored under development and biotic stresses namely PAMPs treatment and bacterial infection. The information generated here will be of high relevance to better target the H2S metabolism to enhance the tomato prospects and also serve a preliminary investigation to be adopted in other agronomic important crops.

scholarly journals Liquid-Liquid Phase Separation Phenomenon on Protein Sorting Within Chloroplasts

2021 ◽  
Vol 12 ◽  
Author(s):  
Canhui Zheng ◽  
Xiumei Xu ◽  
Lixin Zhang ◽  
Dandan Lu
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Higher Plants ◽  
Protein Sorting ◽  
Liquid Phase Separation ◽  
Future Research ◽  
The Novel ◽  
Proper Functions ◽  
Cellular Compartments ◽  
Liquid Liquid Phase Separation

In higher plants, chloroplasts are vital organelles possessing highly complex compartmentalization. As most chloroplast-located proteins are encoded in the nucleus and synthesized in the cytosol, the correct sorting of these proteins to appropriate compartments is critical for the proper functions of chloroplasts as well as plant survival. Nuclear-encoded chloroplast proteins are imported into stroma and further sorted to distinct compartments via different pathways. The proteins predicted to be sorted to the thylakoid lumen by the chloroplast twin arginine transport (cpTAT) pathway are shown to be facilitated by STT1/2 driven liquid-liquid phase separation (LLPS). Liquid-liquid phase separation is a novel mechanism to facilitate the formation of membrane-less sub-cellular compartments and accelerate biochemical reactions temporally and spatially. In this review, we introduce the sorting mechanisms within chloroplasts, and briefly summarize the properties and significance of LLPS, with an emphasis on the novel function of LLPS in the sorting of cpTAT substrate proteins. We conclude with perspectives for the future research on chloroplast protein sorting and targeting mechanisms.

scholarly journals PDIL1-2 can indirectly and negatively regulate expression of the AGPL1 gene in bread wheat

2019 ◽  
Vol 52 (1) ◽  
Author(s):  
Jie Dong ◽  
Yongxing Zheng ◽  
Yihan Fu ◽  
Jinxi Wang ◽  
Shasha Yuan ◽  
...  
Keyword(s):  
Higher Plants ◽  
Large Subunit ◽  
Functional Characterization ◽  
Starch Biosynthesis ◽  
Kernel Weight ◽  
Starch Accumulation ◽  
Virus Induced Gene Silencing ◽  
Gene Encoding ◽  
Key Enzyme ◽  
And Function

Abstract Background ADP-glucose pyrophosphorylase (AGPase), the key enzyme in plant starch biosynthesis, is a heterotetramer composed of two identical large subunits and two identical small subunits. AGPase has plastidial and cytosolic isoforms in higher plants, whereas it is mainly detected in the cytosol of grain endosperms in cereal crops. Our previous results have shown that the expression of the TaAGPL1 gene, encoding the cytosolic large subunit of wheat AGPase, temporally coincides with the rate of starch accumulation and that its overexpression dramatically increases wheat AGPase activity and the rate of starch accumulation, suggesting an important role. Methods In this study, we performed yeast one-hybrid screening using the promoter of the TaAGPL1 gene as bait and a wheat grain cDNA library as prey to screen out the upstream regulators of TaAGPL1 gene. And the barley stripe mosaic virus-induced gene-silencing (BSMV-VIGS) method was used to verify the functional characterization of the identified regulators in starch biosynthesis. Results Disulfide isomerase 1-2 protein (TaPDIL1-2) was screened out, and its binding to the TaAGPL1-1D promoter was further verified using another yeast one-hybrid screen. Transiently silenced wheat plants of the TaPDIL1-2 gene were obtained by using BSMV-VIGS method under field conditions. In grains of BSMV-VIGS-TaPDIL1-2-silenced wheat plants, the TaAGPL1 gene transcription levels, grain starch contents, and 1000-kernel weight also significantly increased. Conclusions As important chaperones involved in oxidative protein folding, PDIL proteins have been reported to form hetero-dimers with some transcription factors, and thus, our results suggested that TaPDIL1-2 protein could indirectly and negatively regulate the expression of the TaAGPL1 gene and function in starch biosynthesis.

Subcellular Localization of Amylose Precipitating Factor in Neurospora

1982 ◽  
Vol 40 ◽  
pp. 312-313
Author(s):  
Jacob P. Varkey ◽  
Mathew J. Nadakavukaren ◽  
Derek A. McCracken
Keyword(s):  
Subcellular Localization ◽  
Higher Plants ◽  
Starch Biosynthesis ◽  
Short Chain ◽  
Distinguishing Characteristic ◽  
Fungal Hyphae ◽  
Precipitating Factor

Amylose precipitating factor (APF) is a lipoprotein first found associated with starch in some fungi. Since then, APF has been reported from many organisms. The ability of the lipoprotein to bind to short chain amylose molecules and precipitate them is used as a distinguishing characteristic. Starch produced by certain fungi consists of short chain amylose molecules. Even though these fungi have the enzymes needed for the formation of large amylose molecules as in higher plants, the reason for the formation of short chain amylose is not known. Since APF is associated with short chain amylose molecules, we were interested in studying the effect of APF on the fungal starch biosynthesis. In this paper we describe the localization of APF in the fungal hyphae.

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