Overexpression of a glycogenin, CmGLG2, enhances floridean starch accumulation in the red alga<i>Cyanidioschyzon merolae</i>

Pancha, Imran; Tanaka, Kan; Imamura, Sousuke

doi:10.1080/15592324.2019.1596718

Cited by 8 publications

(8 citation statements)

References 30 publications

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“…Most of the proteins involved in starch initiation in plants seem to be absent in these groups. Interestingly, it has been suggested that glycogenin‐like proteins are present in the red alga Cyanidioschyzon merolae (Pancha et al ., 2019), but more work is needed to show that the initiation of Floridean starch formation is similar to the initiation of glycogen formation.…”

Section: Evolutionary Conservation Of the Starch Granule Formation Initiation Mechanismmentioning

confidence: 99%

Starch granule initiation in Arabidopsis thaliana chloroplasts

Mérida

Fettke

2021

The Plant Journal

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SUMMARY The initiation of starch granule formation and the mechanism controlling the number of granules per plastid have been some of the most elusive aspects of starch metabolism. This review covers the advances made in the study of these processes. The analyses presented herein depict a scenario in which starch synthase isoform 4 (SS4) provides the elongating activity necessary for the initiation of starch granule formation. However, this protein does not act alone; other polypeptides are required for the initiation of an appropriate number of starch granules per chloroplast. The functions of this group of polypeptides include providing suitable substrates (maltooligosaccharides) to SS4, the localization of the starch initiation machinery to the thylakoid membranes, and facilitating the correct folding of SS4. The number of starch granules per chloroplast is tightly regulated and depends on the developmental stage of the leaves and their metabolic status. Plastidial phosphorylase (PHS1) and other enzymes play an essential role in this process since they are necessary for the synthesis of the substrates used by the initiation machinery. The mechanism of starch granule formation initiation in Arabidopsis seems to be generalizable to other plants and also to the synthesis of long‐term storage starch. The latter, however, shows specific features due to the presence of more isoforms, the absence of constantly recurring starch synthesis and degradation, and the metabolic characteristics of the storage sink organs.

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Section: Evolutionary Conservation Of the Starch Granule Formation Initiation Mechanismmentioning

confidence: 99%

Starch granule initiation in Arabidopsis thaliana chloroplasts

Mérida

Fettke

2021

The Plant Journal

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“…Regulation proteins such as TFs, TRs, as well as those involved in post-translational modification, are representing the most promising targets for rewiring carbon partitioning for enhancing production of starches or lipids in microalgae. Recently, the target of rapamycin signaling pathway was found to be involved in starch accumulation via mediating phosphorylation of a glycogenin-like protein (CmGLG1) in the unicellular red alga Cyanidioschyzon merolea , and overexpression of CmGLG1 resulted in 4.7-fold increase in the starch content ( Pancha et al, 2019a ; Pancha et al, 2019b ). An earlier study showed knocking out a Zn (II) 2 Cys 6 gene improved partitioning of the total carbon to lipid from 20 to 40–55% in Nannochloropsis ( Ajjawi et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Identification and Biotechnical Potential of a Gcn5-Related N-Acetyltransferase Gene in Enhancing Microalgal Biomass and Starch Production

Cao

Zhao

et al. 2020

Front. Plant Sci.

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Microalgae are promising feedstocks for starch production, which are precursors for bioenergy and chemicals manufacturing. Though starch biosynthesis has been intensively studied in the green alga Chlamydomonas reinhardtii , regulatory mechanisms governing starch metabolism in this model species have remained largely unknown to date. We proposed that altering triacylglycerol (TAG) biosynthesis may trigger intrinsic regulatory pathways governing starch metabolism. In accordance with the hypothesis, it was observed in this study that overexpression of the plastidial lysophosphatidic acid acyltransferase gene (i.e. LPAAT1 ) in C. reinhardtii significantly enhanced TAG biosynthesis under nitrogen (N)-replete conditions, whereas the starch biosynthesis was enhanced in turn under N depletion. By the exploitation of transcriptomics analysis, a putative regulatory gene coding Gcn5-related N-acetyltransferase ( GNAT19 ) was identified, which was up-regulated by 11–12 times in the CrLPAAT1 OE lines. Overexpression of the cloned full-length CrGNAT19 cDNA led to significant increase in the starch content of C. reinhardtii cells grown under both N-replete and N-depleted conditions, which was up to 4 times and 26.7% higher than that of the empty vector control, respectively. Moreover, the biomass yield of the CrGNAT19 OE lines reached 1.5 g L -1 after 2 days under N-depleted conditions, 72% higher than that of the empty vector control (0.87 g L -1 ). Overall, the yield of starch increased by 118.5% in CrGNAT19 OE lines compared to that of the control. This study revealed the great biotechnical potentials of an unprecedented GNAT19 gene in enhancing microalgal starch and biomass production.

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“…Homologs of glycogen synthase (27) and glycogen phosphorylase (28) regulate the accumulation of amylopectin in this parasite, and TgGat1 has been annotated as a glycogenin (28,29). Related genes have been implicated in promoting starch formation in red algae (30,31). Thus, Gat1 might have a function in regulating T. gondii amylopectin formation.…”

Section: Gat1 Is Closely Related To Glycogeninmentioning

confidence: 99%

A terminal α3-galactose modification regulates an E3 ubiquitin ligase subunit in Toxoplasma gondii

Mandalasi

Kim

Thieker

et al. 2020

Journal of Biological Chemistry

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Skp1, a subunit of E3 Skp1/Cullin-1/F-box protein ubiquitin ligases, is modified by a prolyl hydroxylase that mediates O2 regulation of the social amoeba Dictyostelium and the parasite Toxoplasma gondii. The full effect of hydroxylation requires modification of the hydroxyproline by a pentasaccharide that, in Dictyostelium, influences Skp1 structure to favor assembly of Skp1/F-box protein subcomplexes. In Toxoplasma, the presence of a contrasting penultimate sugar assembled by a different glycosyltransferase enables testing of the conformational control model. To define the final sugar and its linkage, here we identified the glycosyltransferase that completes the glycan and found that it is closely related to glycogenin, an enzyme that may prime glycogen synthesis in yeast and animals. However, the Toxoplasma enzyme catalyzes formation of a Galα1,3Glcα linkage rather than the Glcα1,4Glcα linkage formed by glycogenin. Kinetic and crystallographic experiments showed that the glycosyltransferase Gat1 is specific for Skp1 in Toxoplasma and also in another protist, the crop pathogen Pythium ultimum. The fifth sugar is important for glycan function as indicated by the slow-growth phenotype of gat1Δ parasites. Computational analyses indicated that, despite the sequence difference, the Toxoplasma glycan still assumes an ordered conformation that controls Skp1 structure and revealed the importance of nonpolar packing interactions of the fifth sugar. The substitution of glycosyltransferases in Toxoplasma and Pythium by an unrelated bifunctional enzyme that assembles a distinct but structurally compatible glycan in Dictyostelium is a remarkable case of convergent evolution, which emphasizes the importance of the terminal α-galactose and establishes the phylogenetic breadth of Skp1 glycoregulation.

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Overexpression of a glycogenin, CmGLG2, enhances floridean starch accumulation in the red algaCyanidioschyzon merolae

Cited by 8 publications

References 30 publications

Starch granule initiation in Arabidopsis thaliana chloroplasts

Starch granule initiation in Arabidopsis thaliana chloroplasts

Identification and Biotechnical Potential of a Gcn5-Related N-Acetyltransferase Gene in Enhancing Microalgal Biomass and Starch Production

A terminal α3-galactose modification regulates an E3 ubiquitin ligase subunit in Toxoplasma gondii

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