Abstract
Carbohydrate-binding modules (CBMs), as an important auxiliary module, play a key role in degrading soluble alginate by alginate lyase, but the function on alginate gel has not been elucidated. Recently, we reported alginate lyase VxAly7B containing a CBM32 and a polysaccharide lyase family 7 (PL7). To investigate the specific function of CBM32, we characterized the full-length alginate lyase VxAly7B (VxAly7B-FL) and truncated mutants VxAly7B-CM (PL7) and VxAly7B-CBM (CBM32). Both VxAly7B-FL and native VxAly7B can spontaneously cleavage between CBM32 and PL7. The substrate-binding capacity and activity of VxAly7B-CM to soluble alginate were 0.86- and 1.97-fold those of VxAly7B-FL, respectively. Moreover, CBM32 could accelerate the expansion and cleavage of alginate gel beads, and the degradation rate of VxAly7B-FL to alginate gel beads was threefold that of VxAly7B-CM. Results showed that CBM32 is not conducive to the degradation of soluble alginate by VxAly7B but is helpful for binding and degradation of insoluble alginate gel. This study provides new insights into the function of CBM32 on alginate gel, which may inspire the application strategy of CBMs in insoluble substrates.
Highlights
Brown algae, important marine primary producers (Enríquez and Borowitzka, 2010), constitute a large amount of biomass in marine ecosystems (Duarte et al, 2004; Roesijadi et al, 2010; Wargacki et al, 2012)
More than 3,000 bacterial strains were isolated from four seawater samples, of which 12 strains with high enzyme activity reached more than 10 U/mL
The results showed that recombinant VxAly7B-FL would spontaneously cleavage between CBM32 and the catalytic domain, similar to the native enzyme (Supplementary Figure 4)
Summary
Important marine primary producers (Enríquez and Borowitzka, 2010), constitute a large amount of biomass in marine ecosystems (Duarte et al, 2004; Roesijadi et al, 2010; Wargacki et al, 2012). Alginate is the most abundant polysaccharide in brown algae, accounting for approximately 40% of its dry weight (Chung et al, 2011; Popper et al, 2011). Alginate gel has received extensive attention in the field of tissue engineering due to its excellent biocompatibility and controllable release characteristics as a carrier of living cells (Nguyen and Anker, 2014). As a tough, elastic, non-thermally reversible colloidal material, alginate gel is favored in agriculture and food fields because of its use to encapsulate metabolites such as endosulfan, curcumin, and astaxanthin (Bozanic et al, 2009; Song et al, 2012, 2020). Enzymatic degradation is less stimulating to cells and can control the release rates of small molecular compounds, which has become a hot spot in current research
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call