Fig. 6

Hypothetical model proposing how AnAXE1 could affect lignin and xylan solubility in transgenic lines. Deacetylation of xylan is hypothesized to render it more susceptible to cell wall-resident family GH10 transglycosylases such as PtxtXYN10A [32] and endoxylanases. GH10 enzymes do not tolerate substitutions at subsite −1 due to steric hindrance [39], and therefore, xylan domains with acetylation at consecutive Xylp units are expected to be protected from these enzymes. As found in [5, 6], the majority of xylan present in secondary walls has acetylation on alternate Xylp units, and such xylan domains have been proposed to interact with hydrophilic side of cellulose microfibrils [6]. Only minor xylan domains have acetylation on consecutive Xylp [5, 6], and it was reasoned that such acetylation pattern precludes the binding to cellulose [6]. However, these regions are expectedly available for interactions with lignin, for example, via MeGlcA side chains. Deacetylation of these minor domains would have rendered them even more prone to interaction with lignin via newly available OH groups on Xylp as proposed in [33], and to hydrolysis by GH10, as discussed above. Consequently, these domains along with their associated lignin polymers would be liberated from the cellulose-xylan network in AnAXE1 expressing lines