Structure-Function Analysis of the Bacterial Expansin EXLX1 *

摘要: We made use of EXLX1, an expansin from Bacillus subtilis, to investigate protein features essential for its plant cell wall binding and loosening activities. found that the two domains, D1 D2, need be linked extension activity D2 mediates EXLX1 whole walls cellulose via distinct residues on surface. Binding is mediated by three aromatic arranged linearly putative surface spans D2. Mutation these alanine eliminated concomitantly measured either or weakening filter paper but hardly affected walls, which basic located other surfaces. glutamine reduced not propose domain as founding member a new carbohydrate module family, CBM63, function in apparently goes beyond simply anchoring wall. Several polar are also important activity, most notably Asp82, whose mutation asparagine completely activity. The functional insights based this bacterial may extrapolated interactions expansins with walls.