Engineering of cyclodextrin glycosyltransferase reveals pH-regulatory mechanism of enhanced long chain glycosylated sophoricoside specificity.

Engineering of cyclodextrin glycosyltransferase reveals pH-regulatory mechanism of enhanced long chain glycosylated sophoricoside specificity. Appl Environ Microbiol. 2020 Jan 31;: Authors: Han R, Ni J, Zhou J, Dong J, Xu G, Ni Y Abstract Sophoricoside glycosylated derivatives, especially long chain glycosylated sophoricosides (LCGS) have greatly improved water solubility compared with sophoricoside. Here cyclodextrin glycosyltransferase from Paenibacillus macerans (PmCGTase) was employed for sophoricoside glycosylation. Saturation mutagenesis of alanine 156, alanine 166, glycine 173, and leucine 174 were performed due to their non-conservative properties among (α-, β-, and γ-) CGTases with different product specificities. Variants L174P, A156V/L174P, and A156V/L174P/A166Y greatly improved the product specificity for LCGS. pH significantly affected the extent of glycosylation catalyzed by the variants. Further investigations revealed that the pH-regulatory mechanism for LCGS synthesis mainly depends on a disproportionation route at a lower pH (pH 4) and a cyclization-coupling route at a higher pH (pH 8), and equivalent effects of cyclization-coupling and disproportionation routes at pH 5. Whereas SCGS are primarily produced via disproportionation of maltodextrin at pH 4 and secondary disproportionation of LCGS at pH 8. At pH 5, SCGS synthesis mainly depends on a hydrolysis route by WT and a secondary disproportionation route by A1...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research