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The starch metabolic network was investigated in relation to other metabolic processes by examining a mutant with altered single-gene expression of ATP citrate lyase (ACL), an enzyme responsible for generating cytosolic acetyl-CoA pool from citrate. Previous research has shown that transgenic antisense plants with reduced ACL activity accumulate abnormally enlarged starch granules. In this study, we explored the underlying molecular mechanisms linking cytosolic acetyl-CoA generation and starch metabolism under short-day photoperiods. We performed transcriptome and quantification of starch accumulation in the leaves of wild-type and antisense seedlings with reduced ACL activity. The antisense-ACLA mutant accumulated more starch than the wild type under short-day conditions. Zymogram analyses were conducted to compare the activities of starch-metabolizing enzymes with transcriptomic changes in the seedling. Differential expression between wild-type and antisense-ACLA plants was detected in genes implicated in starch and acetyl-CoA metabolism, and cell wall metabolism. These analyses revealed a strong correlation between the transcript levels of genes responsible for starch synthesis and degradation, reflecting coordinated regulation at the transcriptomic level. Furthermore, our data provide novel insights into the regulatory links between cytosolic acetyl-CoA metabolism and starch metabolic pathways.
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Regulation of ATP-Citrate Lyase During Lipogenesis in the Oleaginous Yeast Yarrowia lipolytica
ATP citrate lyase (ACL) catalyzes the ATP-dependent conversion of citrate to the fatty acid precursor, acetyl-CoA. ACL presence in yeasts has been associated with their ability to accumulate lipids (i.e., oleaginous phenotype), but little is known about the regulation of this enzyme in oleaginous yeasts. In the model oleaginous yeast Yarrowia lipolytica, ACL is a heterodimer comprised of a catalytic and a regulatory subunit, encoded by the ACL1 and ACL2 genes, respectively. From the earlier studies, it was shown that the loss of ACL1 resulted in lower lipid levels and altered fatty acid profiles. However, the regulation of ACL expression and activity during lipogenesis has not been studied. To better understand the role, ACL plays during lipogenesis in Y.lipolytica, we generated antibodies against its two subunits (i.e., Acl1 and Acl2). We also constructed strains that lack Acl2 (i.e., acl2Δ) and strains that overexpress Acl1 and Acl2 either alone or in combination. Preliminary experiments showed that the overexpression of Acl1 increased the protein levels of Acl2. We are currently analyzing the effects of Acl2 overexpression and the time-dependent regulation of Acl1 and Acl2.
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- Award ID(s):
- 2100980
- PAR ID:
- 10351346
- Date Published:
- Journal Name:
- The FASEB journal
- Volume:
- 36
- Issue:
- S1
- ISSN:
- 1530-6860
- Page Range / eLocation ID:
- 0892-6638
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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