What is Trehalose?

1
What is Trehalose?

• Non-reducing disaccharide joint by two glucoses
• Stores carbohydrate
• Protects cells against various stress conditions

2
How is Trehalose Made?
Trehalose
3
Where is Trehalose Found?

• Before 1997, trehalose was thought to be present
  in a few desiccation-tolerant plants

Selaginella lepidophylla Resurrection Plants
4
Trehalose in Saccharomyces cerevisiae

• In yeast, TPS and TPP function together as a
  large complex to synthesize trehalose
• TPS1 is found to be important in regulating
  glucose glycolysis
• ATP is consumed to drive glucose catabolism
• When glucose increases suddenly, glycolysis
  would use up ATP so fast that stalls metabolism
• Trehalose-6-phosphate targets the initial step of
  glycolysis to restrict the influx of glucose into
  glycolysis

5
Sugar Flux Through Glycolysis Trehalose
Metabolism in Yeast
Sucrose Synthase
Glucose Glycolysis
Trehalose Metabolism
Hexokinase
6
Trehalose in Escherichia Coli

• T-6-P synthesis is catayzed by the retaining
  glucosyltransferase OtsA
• OtsA is structurally similar to glycogen
  phosphorylase, suggesting a common catalytic
  mechanism

7
Is Trehalose Synthesis Pathway also Important in
Plants?
Trehalose is detected!! They are known to be high
desiccation tolerant.
Resurrection plant
Resurrection bush
Trehalose is undetected. Is trehalose
only related to desiccation tolerance?
Arabidopsis
Rice
8
Is Trehalose Present in Angiosperms?
Tobacco
Trehalose can be detected when enzymatic
activity of trehalase is inhibited!!
What is the function of trehalose (synthesis
pathway)? Are there other functions, like
glycolysis regulation, than high desiccation
tolerance?
Potato
9
Arabidopsis Genome Contains Several Homologs of
Enzymes Known to be Involved in Trehalose
Synthesis Pathway.
10
What is the Phenotype of the tps1 Mutant?
Embryo development in the tps1 mutant is arrested
at the torpedo stage.
11
What is Happening at the Torpedo Stage?
Torpedo stage is a kind of transition stage from
cell division and differentiation to cell
expansion and storage reserve accumulation.
12
Is Embryo Developmental Arrest Caused by a Defect
in Glycolysis Regulation?

• Low level of sugar in media somehow rescues
• the mutant phenotype, but not completely.
• In Arabidopsis, T-6-P is not the inhibitor of
  HXK.
• Glycolysis regulation in
• trehalose synthesis pathway
• is different from that in yeast.
• Even inhibition of HXK
• activity does not rescue
• the mutant phenotype.
• Disruption of regulation in
• glucose influx into glycolysis is not the main
  reason
• for the phenotype of the tps1 mutant.

What causes embryo lethal in the tps1 mutant?
13
Can Trehalose Rescue Embryo Developmental Arrest
in tps1 Mutant?
As T-6-P cannot be absorbed into plant
cells, this type of experiment cannot be done
with T-6-P.
14
In Conclusion,
Trehalose-6-phosphate synthase (TPS) is important
for embryo development. However, it is unclear
whether the trehalose synthesis pathway itself is
important for embryo development. Indeed,
trehalose does not rescue the tps1 mutant
phenotype. TPS could be involved in sugar
signaling. As sucrose level increases
dramatically in torpedo stage, this might
trigger TPS involved sugar signaling, and this
might be important for embryo development, other
than trehalose synthesis pathway. Glycolysis
regulation involving trehalose synthesis pathway
in yeast is different from that in Arabodopsis.
15
Commercial Usage of Trehalose

• Producing stress-tolerent crops

16
Commercial Values in Medical Fileds

• Demand for having human blood cells and platelets
  to have extended shelf-life
• Freezing dehydrating cells could kill a
  substantial numbers of them
• Application of chemicals to preserve cells are
  not appropriate either because most of the
  chemicals are toxic
• Trehalose might solve the problem
• Non-toxic
• Replaces some water in the cell to prevent
  uncontrolled dehydration
• Stabilizes the cell membrane and prevents
  disintegration
• Forms amorphous glass inside the cells,
  preventing ice crystals from forming
• 90 recovery of platelets

17
Treatment Potential of Trehalose in Huntingtons
Disease

• Trehalose could prevent the development of the
  brain pathology associated with Huntington
  disease by inhibiting aggregate formation the ine
  brain.