Trehalose-6-phosphate Synthesis in Streptomyces is Related to a New GDP-glucose Pyrophosphorylase

ASENCIÓN DIEZ, MD; SYSON, K; MIAH, F; BORNEMANN, S; IGLESIAS, AA

Mar del Plata

Congreso; LI Reunión Anual de SAIB; 2015

SAIB

The non-reducing disaccharide trehalose ( -D-glucopyranosyl-(1,1)- -D-glucopyranoside, Tre) is a compatible solute stabilizing cell membranes and protein structures. It protects cells against different types of stresses and can serve as a carbon source or storage molecule. In some actinomycetes, Tre has a structural role and it is found as a cytoplasmic sugar in active turnover. The OtsAB route is the main Tre source in organisms synthesizing the disaccharide. Interestingly, in the group Actinobacteria, the key pathway enzyme Tre-6P synthase (EC 2.4.1.15; OtsA) exhibits particularities regarding nucleoside diphospho-glucose consumption, being highly specific for GDP-glucose in Streptomyces, as shown in this work. This scenario with the StreptomycesOtsA is supported by biochemical andgenetic experiments. We further analyzed two putative pyrophosphorylases (PPases) from S. venezuelae to understand the glucose-1P routing towards Tre via GDP-Glc. Indeed, we found a specific GDP-GlcPPase (EC. 2.7.7.34), which had not been identified in prokaryotes to date. Thus, a pathway involving the intermediate GDP-Glc could be proposed, a feature never reported so far in any organism.