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Jiang, Nan accepted dissertation 07-17-15 Su 15.pdf (20.38 MB)
ETD Abstract Container
Abstract Header
Characterization of TaXPol-1, a Xylan Synthase Complex from Wheat
Author Info
Jiang, Nan
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1437153132
Abstract Details
Year and Degree
2015, Doctor of Philosophy (PhD), Ohio University, Environmental and Plant Biology (Arts and Sciences).
Abstract
It is believed that Golgi-localized, multi-protein complexes synthesize plant hemicellulosic polysaccharides. However, such complexes are not well characterized in plants, which is in sharp contrast with mammalian and yeast cells. This dissertation describes the characterization of the first hemicellulose synthase complex involved in xylan biosynthesis in wheat (named a Xylan Polymerase-1, TaXPol-1). Xylan is the most abundant plant hemicellulosic polysaccharide on Earth and plays an important role in the integrity of cell walls. It consists of a ß-(1,4)-linked xylose backbone that can be substituted with a-(1,2)-D-glucuronic acid residues and/or a-L-arabinofuranosyl residues at the C-2 and/or C-3 positions of xylose residues. A xylan synthase activity was immuno-purified from etiolated wheat seedlings and its protein composition determined by proteomics analysis. Four glycosyltransferases (GTs) were identified: CAZy GT43 family member (named TaGT43-4), GT47 family member (named TaGT47-13), and two GT75 family members (named TaGT75-3 and TaGT75-4). In addition, two new proteins were identified: a germin-like protein (TaGLP) belonging to the cupin family and a 26kDa protein annotated as vernalization-related 2 (TaVER2). Heterologous co-expression of
TaGT43-4, TaGT47-13, TaGT75-3, TaGT75-4,
and
TaGLP
in
Pichia pastoris
cells resulted in reconstitution of xylan synthase activity in micosomes from transgenic yeast lines. The results showed that (
i
) TaGT43-4 and TaGT47-13 form a central core that is necessary and sufficient for synergistic incorporation of xylose and glucuronic acid, but requires TaGT75-3 and/or TaGT75-4 (putative mutases) for synergistic incorporation of xylose and arabinose, and (
ii
) TaGLP was needed for optimal xylan synthase activity. Furthermore, radio labeled products generated by microsomes from transgenic yeast cells have xylan characteristics. Bimolecular fluorescence complementation (BiFC) and confocal microscopy were used to show that TaGT43-4 interacts with TaGT47-13, TaGT75-3, TaGT75-4, and TaGLP, and these proteins assemble into a complex in the endoplasmic reticulum (ER) before export to the
trans
-Golgi. Importantly, ER export of TaXPol-1 requires that TaGT43-4 and TaGT47-13 interact.
Committee
Faik Ahmed (Advisor)
Showalter Allan (Committee Member)
Kieliszewski Marcia (Committee Member)
Held Michael (Committee Member)
Pages
205 p.
Subject Headings
Biochemistry
;
Biology
;
Botany
;
Plant Biology
;
Plant Sciences
Keywords
Plant cell wall
;
xylan
;
co-immunoprecipitation
;
proteomics
;
pichia
;
cofocal microscopy
;
protein complex
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Refworks
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RIS
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Citations
Jiang, N. (2015).
Characterization of TaXPol-1, a Xylan Synthase Complex from Wheat
[Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1437153132
APA Style (7th edition)
Jiang, Nan.
Characterization of TaXPol-1, a Xylan Synthase Complex from Wheat.
2015. Ohio University, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1437153132.
MLA Style (8th edition)
Jiang, Nan. "Characterization of TaXPol-1, a Xylan Synthase Complex from Wheat." Doctoral dissertation, Ohio University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1437153132
Chicago Manual of Style (17th edition)
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Document number:
ohiou1437153132
Download Count:
520
Copyright Info
© 2015, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.