An improved method for the large scale preparation of α,α′-trehalose-6-phosphate

Accessible 6-O mono-detrimethylsilylation at per-O-TMS asymmetric disaccharides and their derivatization

Efficient mono-detrimethylsilylation at C-6 position of per-O-trimethylsilylated protected asymmetric disaccharides was achieved by an inexpensive reagent, ammonium acetate, at room temperature. The newly formed free hydroxyl at the non-reducing end of the product, 2, 3, 4, 2', 3', 4', 6'-heptakis-O-(trimethylsilyl)-d-lactose (2a), was coupled with azido, acetyl groups, and the modified intermediates represented potential precursors for the corresponding primary asymmetric modification of disaccharides. To broaden the usefulness of TMS-intermediates, the glycosylation and esterification occurred on the mono hydroxyl group of 2a simultaneously. Meaningfully trisaccharide derivative 7a was also obtained by utilizing the key intermediate 2a.

Structural Analysis of Binding Determinants of Salmonella typhimurium Trehalose-6-phosphate Phosphatase Using Ground-State Complexes

Trehalose-6-phosphate phosphatase (T6PP) catalyzes the dephosphorylation of trehalose 6-phosphate (T6P) to the disaccharide trehalose. The enzyme is not present in mammals but is essential to the viability of multiple lower organisms as trehalose is a critical metabolite, and T6P accumulation is toxic. Hence, T6PP is a target for therapeutics of human pathologies caused by bacteria, fungi, and parasitic nematodes. Here, we report the X-ray crystal structures of Salmonella typhimurium T6PP (StT6PP) in its apo form and in complex with the cofactor Mg²⁺ and the substrate analogue trehalose 6-sulfate (T6S), the product trehalose, or the competitive inhibitor 4-n-octylphenyl α-d-glucopyranoside 6-sulfate (OGS). OGS replaces the substrate phosphoryl group with a sulfate group and the glucosyl ring distal to the sulfate group with an octylphenyl moiety. The structures of these substrate-analogue and product complexes with T6PP show that specificity is conferred via hydrogen bonds to the glucosyl group proximal to the phosphoryl moiety through Glu123, Lys125, and Glu167, conserved in T6PPs from multiple species. The structure of the first-generation inhibitor OGS shows that it retains the substrate-binding interactions observed for the sulfate group and the proximal glucosyl ring. The OGS octylphenyl moiety binds in a unique manner, indicating that this subsite can tolerate various chemotypes. Together, these findings show that these conserved interactions at the proximal glucosyl ring binding site could provide the basis for the development of broad-spectrum therapeutics, whereas variable interactions at the divergent distal subsite could present an opportunity for the design of potent organism-specific therapeutics.

Efficient one-pot enzymatic synthesis of trehalose 6-phosphate using GH65 α-glucoside phosphorylases

Trehalose 6-phosphate (Tre6P) is an important intermediate for trehalose biosynthesis. Recent researches have revealed that Tre6P is an endogenous signaling molecule that regulates plant development and stress responses. The necessity of Tre6P in physiological studies is expected to be increasing. To achieve the cost-effective production of Tre6P, a novel approach is required. In this study, we utilized trehalose 6-phosphate phosphorylase (TrePP) from Lactococcus lactis to produce Tre6P. In the reverse phosphorolysis by the TrePP, 91.9 mM Tre6P was produced from 100 mM β-glucose 1-phosphate (β-Glc1P) and 100 mM glucose 6-phosphate (Glc6P). The one-pot reaction of TrePP and maltose phosphorylase (MP) enabled production of 65 mM Tre6P from 100 mM maltose, 100 mM Glc6P, and 20 mM inorganic phosphate. Addition of β-phosphoglucomutase to this reaction produced Glc6P from β-Glc1P and thus reduced requirement of Glc6P as a starting material. Within the range of 20-469 mM inorganic phosphate tested, the 54 mM concentration yielded the highest amount of Tre6P (33 mM). Addition of yeast increased the yield because of its glucose consumption. Finally, from 100 mmol maltose and 60 mmol inorganic phosphate, we successfully achieved production of 37.5 mmol Tre6P in a one-pot reaction (100 mL), and 9.4 g Tre6P dipotassium salt was obtained.

Rational design of reversible inhibitors for trehalose 6-phosphate phosphatases

In some organisms, environmental stress triggers trehalose biosynthesis that is catalyzed collectively by trehalose 6-phosphate synthase, and trehalose 6-phosphate phosphatase (T6PP). T6PP catalyzes the hydrolysis of trehalose 6-phosphate (T6P) to trehalose and inorganic phosphate and is a promising target for the development of antibacterial, antifungal and antihelminthic therapeutics. Herein, we report the design, synthesis and evaluation of a library of aryl d-glucopyranoside 6-sulfates to serve as prototypes for small molecule T6PP inhibitors. Steady-state kinetic techniques were used to measure inhibition constants (K_i) of a panel of structurally diverse T6PP orthologs derived from the pathogens Brugia malayi, Ascaris suum, Mycobacterium tuberculosis, Shigella boydii and Salmonella typhimurium. The binding affinities of the most active inhibitor of these T6PP orthologs, 4-n-octylphenyl α-d-glucopyranoside 6-sulfate (9a), were found to be in the low micromolar range. The K_i of 9a with the B. malayi T6PP ortholog is 5.3 ± 0.6 μM, 70-fold smaller than the substrate Michaelis constant. The binding specificity of 9a was demonstrated using several representative sugar phosphate phosphatases from the HAD enzyme superfamily, the T6PP protein fold family of origin. Lastly, correlations drawn between T6PP active site structure, inhibitor structure and inhibitor binding affinity suggest that the aryl d-glucopyranoside 6-sulfate prototypes will find future applications as a platform for development of tailored second-generation T6PP inhibitors.