BackgroundInulosucrase (IslA) from Leuconostoc citreum CW28 belongs to a new subfamily of multidomain fructosyltransferases (FTFs), containing additional domains from glucosyltransferases. It is not known what the function of the additional domains in this subfamily is.ResultsThrough construction of truncated versions we demonstrate that the acquired regions are involved in anchoring IslA to the cell wall; they also confer stability to the enzyme, generating a larger structure that affects its kinetic properties and reaction specificity, particularly the hydrolysis and transglycosylase ratio. The accessibility of larger molecules such as EDTA to the catalytic domain (where a Ca2+ binding site is located) is also affected as demonstrated by the requirement of 100 times higher EDTA concentrations to inactivate IslA with respect to the smallest truncated form.ConclusionThe C-terminal domain may have been acquired to anchor inulosucrase to the cell surface. Furthermore, the acquired domains in IslA interact with the catalytic core resulting in a new conformation that renders the enzyme more stable and switch the specificity from a hydrolytic to a transglycosylase mechanism. Based on these results, chimeric constructions may become a strategy to stabilize and modulate biocatalysts based on FTF activity.

The transition from an economy dependent on nonrenewable energy sources to one with higher diversity of renewables will not be a simple process. It requires an important research effort to adapt to the dynamics of the changing energy market, sort costly processes, and avoid overlapping with social interest markets such as food and livestock production. In this review, we analyze the desirable traits of raw plant materials for the bioethanol industry and the molecular biotechnology strategies employed to improve them, in either plants already under use (as maize) or proposed species (large grass families). The fundamentals of these applications can be found in the mechanisms by which plants have evolved different pathways to manage carbon resources for reproduction or survival in unexpected conditions. Here, we review the means by which this information can be used to manipulate these mechanisms for commercial uses, including saccharification improvement of starch and cellulose, decrease in cell wall recalcitrance through lignin modification, and increase in plant biomass.

ITV-01 presents amylolytic activity, identified as α-glucosidase, an enzyme that only produces α-d-glucose from soluble starch and that presents transglucosylase activity on α-d-glucopyranosyl-(1-4)-α-d-glucopyranose (maltose) (200 gL). Biochemical characterization was performed on ITV-01 α-glucosidase; its optimum parameters were pH 4.3, temperature 80 °C but stable at 40 °C, with an energy of activation (Ea) 176.25 kJ mol. Using soluble starch as the substrate, and were 5 mg mL and 1000 U mg, respectively. As α-glucosidase is not a metalloenzyme, calcium and EDTA did not have any effect on its activity. The molecular weight was estimated by SDS-PAGE to be about 75 kDa. It was also active in methanol and ethanol. When ammonium sulfate (AS) and yeast extract (YE) nitrogen sources and calcium effect were evaluated, the greatest activity occurred using YE and calcium, as opposed to AS media where no activity was detected. The results obtained showed that this enzyme has industrial application potential in the processes to produce either ethanol or malto-oligosaccharides from α-d-glucopyranosyl-(1-4)-α-d-glucopyranose (maltose).