Premium
Mutational analysis of the role of calcium ions in the Lactobacillus reuteri strain 121 fructosyltransferase (levansucrase and inulosucrase) enzymes
Author(s) -
Ozimek L.K.,
Euverink G.J.W.,
van der Maarel M.J.E.C.,
Dijkhuizen L.
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2004.11.113
Subject(s) - lactobacillus reuteri , levansucrase , bacillus subtilis , biochemistry , enzyme , chemistry , lipid ii , cofactor , bacteria , biology , lactobacillus , peptidoglycan , genetics , fermentation
Bacterial fructosyltransferase enzymes belonging to glycoside hydrolase family 68 (GH68) are not known to require a metal cofactor. Here, we show that Ca 2+ ions play an important structural role in the Lactobacillus reuteri 121 levansucrase (Lev) and inulosucrase (Inu) enzymes. Analysis of the Bacillus subtilis Lev 3D structure [Meng, G. and Futterer, K. (2003) Nat. Struct. Biol. 10, 935–941] has provided evidence for the presence of a bound metal ion, most likely Ca 2+ . Characterization of site‐directed mutants in the putative Ca 2+ ion‐binding sites of Lb. reuteri Lev and Inu revealed that the Inu Asp520 and Lev Asp500 residues play an important role in Ca 2+ binding. Sequence alignments of family GH68 proteins showed that this Ca 2+ ion‐binding site is (largely) present only in proteins of Gram‐positive origin.