Elucidation and Characterization of Glycosyltransferases Implicated in Pectic Polysaccharide Biosynthesis in Arabidopsis thaliana

The cell wall is a complex extracellular matrix composed of cellulose, hemicellulose, and pectic polysaccharides that confers multiple functions to plant cells and the plant as an organism. Glycosyltransferases (GTs) are enzymes that catalyze the transfer of a sugar molecule from an activated sugar-nucleotide donor to an acceptor substrate, and these enzymes are responsible for cell wall polysaccharide synthesis. Across plant and metazoan organisms, mutant phenotypes for many GTs result in developmental defects, some of which can be embryonic lethal. This work first describes the expansion upon our laboratory's previous findings that mutation of Arabidopsis thaliana OFUCOSYLTRANSFERASE1 (OFT1) gene resulted in decreased pollen tube penetration through the stigma-style interface. Here, we demonstrate that second site mutations of Arabidopsis GALACTURONOSYLTRANSFERASE14 (GAUT14) and GALACTURONOSYLTRANSFERASE-LIKE4 (GATL4) effectively suppress the phenotype of oft1 mutants, partially restoring silique length, seed set, pollen transmission, and pollen tube penetration deficiencies in navigating the female reproductive tract. Following this story, this work describes the function of Arabidopsis FRIABLE1 (FRB1; RRT8) as a Rhamnogalacutronan-I: Rhamnosyltransferase (RRT). FRB1 displays robust RRT activity compared to genetically related enzymes, and protein structure-function investigations described here shed light on the catalytic function of RRTs. Broadly, this dissertation elaborates on genetic interactions occurring between GTs that are implicated in cell-cell interactions during pollen-pistil interactions and defines the function of a previously understudied GT with kinetic parameter characterization and identification of critical residues for catalysis. This work provides information for future studies and doctoral projects revolving around cell wall biosynthesis, plant cell signaling, and amino acid conservation among GTs that are critical for catalysis.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctorate Degree

Grantor

University of Nevada, Reno

Year dc:date.issued

2024

Author dc:creator

• Robichaux, Kayleigh Jordan

Advisor dc:contributor.advisor

• Wallace, Ian

Committee members dc:contributor.committeemember

• Harper, Jeffrey
• Choi, Won-Gyu
• Cushman, John
• Raeeszadeh-Sarmazdeh, Maryam

• Arabidopsis
• Cell Wall Biosynthesis
• Glycobiology
• Glycosyltransferases
• Pectic Polysaccharides
• Protein O-fucosyltransferases

Repository record dc:identifier.uri

https://scholarwolf.unr.edu/handle/11714/11066

OAI identifier oai:identifier

oai:scholarwolf.unr.edu:11714/11066