OtsA–OtsB pathway Trehalose biosynthesis

Trehalose G6P UDP-G trehalose 6-phosphate OtsA OtsB 1-O- α -D-glucopyranosyl- α -D-glucopyranoside inhibites

1. OtsA–OtsB pathway

Trehalose 6 P T6P Figure 2: Trehalose biosynthesis. Three pathways Smet et al. 2000. 1. OtsA- OtsB pathway, 2. TreY-TreZ pathway and 3. TreS pathway. Avonce et al 2006 proved the presence of 2 other pathways beside the 3 mentioned, distributed in diverse organisms called as TreP 4 th pathway and TreT the 5 th pathways. oligomere. Third pathway called TreS pathway, one enzymatic reaction involves in the pathway, by which enzyme trehalose synthase TRES convert maltose to trehalose. Similarly to the second pathway, this enzyme also rearrange intermolecular of maltose from α 1-4 glycosidic linkage to α - α , 1-1 glycosidic linkage of trehalose, hence maltose is converted to trehalose. This enzyme is also capable to convert trehalose to maltose Smet et al. 2000 with equilibrium state at 60 trehalose and 40 maltose Wei et al. 2004. Avonve et al 2006 proved 2 others pathways beside these pathways, they are called as TreP and TreT pathways Figure 2. TreP pathway, converts glucose-1P and glucose to trehalose and release Pi catalysed by trehalose phosphorylase TreP. This pathway mainly occurs in eubacteria and small portion occurs in archaea. TreT pathway converts ADP-glucose and glucose to produce trehalose and ADP is released. This conversion is catalysed by trehalose glycolsiltransfering synthase, 4. TreP Pathway TreP OP ADP TreT 5. TreT Pathway G-1P Glucose ADP-G and is found mainly in archaea with small event in eubacteria Figure 3. The first pathway is widely spread in many organisms, E. coli Murata et al. 1971 and S. cerevisiae Smet et al. 2001; S. pombe Franco et al. 2000; Aspergillus nidulan Fillinger et al. 2001; A. niger Wolschek and Kubicek, 1997; Soto et al. 1999 and also in Arabidopsis thaliana Leymann et al. 2001. The second pathway can be found such as in Brevibacterium helvolvum Kim et al. 2000, Arthrobacter Nakada et al. 1995, Rizobium Murata et al. 1996 and Archeon Sulfolobus acidocaldarius Murata et al. 1996. While the third pathway can be found in Thermus aquaticus Tsusaki et al. 1997, Agaricus bisphorus Wannet et al. 1998, Pimelobacter Nishimoto et al. 1995, Thermobifida fusca Wei et al. 2004, Thermus acidophyllus and Grifola frondosa Saito et al. 1998. Some organism has more than one pathways, it may be two or three pathways. Mycobacterium tuberculosis Murphy et al. 2005, M. smegmatis, Mycobacterium bovis and M. leprae have those three pathways in trehalose synthesis Pan et al. 2004. Figure 3. Distribution of trehalose pathways in organisms adopted from Avonce et al 2006. Diverse pathways found in eubacteria and archaea, while in eukaryotic organisms the first pathway only is observed and in vertebrates degrading pathway only is available.

2.6 Characterization of Trehalose Synthase TRESTSASE