Improving the catalytic behaviors of Lactobacillus-derived fructansucrases by truncation strategies

Structure–Function Relationship Studies of Multidomain Levansucrases from Leuconostocaceae Family

“…This effect in stability is similar to that reported for the DsrS glucansucrase from Leuconostoc mesenteroides NRRL B-512F, where truncated versions in the C-terminal domain were found to be more susceptible to thermal denaturation [ 34 ]. Recently, Ni et al (2021) observed a decrease in the stability of the N-terminal truncated variants of MD-IS and LS from L. reuteri 121, in accordance with those observed in the MD-IS IslA [ 26 ].…”

“…It is important to highlight that the role of the additional domains has not been studied in other MD-LV from Leuconostoc , and only a few studies have addressed the AD impact in MD-LV from Lactobacillales. Van Hijum et al (2004, 2008) and Ni et al (2021) performed and characterized C- and N-terminal domain truncated versions of MD-IN and MD-LV from Lactobacillus reuteri ; however, they did not compare the effects with the WT versions (both MD-IS and MD-LV) [ 26 , 31 , 32 ]. Del Moral et al (2008) did not report changes in the optimal pH between WT MD-IS IslA and truncated versions in the N- and C-terminal domains [ 28 ].…”

“…In contrast with these results, for IslA MD-IS from L. citreum , no change was observed in the distribution of the HMW polymer produced by IslA and its truncated versions in the N- and C-terminal domains [ 28 ]. In enzymes from the Lactobacillaceae family, the effect of the N-terminal domain on the synthesis capacity of HMW products was also observed in the MD-LS from Lactobacillus reuteri 121; however, in the MD-IS of this same microorganism, the elimination of this region results in some minor changes to the product profiles [ 26 ]. Similarly, the C-terminal truncated version of MD-LS from L. reuteri also did not show any changes in the distribution of synthesized HMW polymers [ 31 ].…”

“…These truncated enzymes displayed different effects on activity, highlighting the truncated IS and LS from L. reuteri , which showed the highest activity among all the truncated versions studied. The authors conclude that N-terminal truncation has little influence on fructan biosynthesis [ 26 ]. These reports suggest that the C- and N-terminal regions in MD-FNs from lactic acid bacteria have low contributions to catalytic activity and specificity [ 37 ].…”

“…Moreover, the results of the limited studies regarding lactobacillus FN’s structure-function relationship are contradictory. Studies regarding fructan production employing truncated lactobacillus FN versions have identified that the additional domains are excluded from the catalytic process, suggesting that their participation is limited to the anchorage of FNs to the membrane of Lactobacillales, or to a lesser extent, to the stability of the protein structure [ 26 , 27 ]. On the other hand, a study of MD-ISs from a Leuconostocaceae family member reported an important participation of the additional domains for catalysis, highlighting their importance for enzyme stability and in the transfructosylation reaction [ 28 ].…”