Interplay of DGAT1, PDAT1 and DGAT2 Enzymes in Plant Triacylglycerol Assembly

<p>Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyzes the transesterification of fatty acid from acyl-CoA to diacylglycerol (DAG) forming triacylglycerol (TAG, a.k.a oils and fats). Most plants have at least two unrelated <em>DGAT</em> genes, <em>DGAT1</em> and <em>DGAT2.</em> Plants predominantly express only one during oil synthesis; the reason, however is not clear. A few studies have indicated that each enzyme prefers DAG and acyl-CoA substrates with different fatty acid compositions. Industrially desirable seed oil composition can be obtained through genetic engineering by replacing the endogenous enzyme with one that has different substrate selectivity. In <em>Arabidopsis thaliana</em>, DGAT1 and another unrelated enzyme PDAT1 are essential for TAG synthesis in seeds and pollen, and the <em>dgat1-1/pdat1-2</em> double knock-out is pollen lethal. However, the role of DGAT2 in Arabidopsis tissues remains elusive. It is hypothesized that DGAT2 isozymes from Arabidopsis, castor, and soybean can synthesize TAG but with altered fatty acid composition and they utilize de novo DAG pools whereas AtDGAT1 and AtPDAT1 use PC-derived DAG pools. To test this hypothesis <em>DGAT2</em>s were overexpressed with a strong seed-specific promoter in the <em>dgat1-1</em> knockout background. Our results suggests that DGAT2s synthesize TAG in seeds with altered fatty acid composition than AtDGAT1 and AtPDAT1. To identify the DAG pool utilized by DGAT1, PDAT1 and different DGAT2s, <em>in vivo</em> labeling was performed utilizing [¹⁴C]glycerol substrate. AtDGAT1 and AtPDAT1 were found to be using the PC-derived DAG pool for TAG synthesis. This study provided initial data that DGAT2s also use the PC-derived DAG pool.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Discipline thesis:degree_discipline

Chemistry and Biochemistry

Year dc:date.available

2018

Author dc:creator

• Regmi, Anushobha

Contributors dc:contributor

• Philip D. Bates
• Sabine Heinhorst
• Faqing Huang

• AtDGAT1
• AtDGAT2
• AtPDAT1
• GmDGAT2
• RcDGAT2
• Arabidopsis
• AS11
• Plant Biology
• Plant Breeding and Genetics

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/365

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1397