title: Single amino acid residue changes in subsite -1 of levansucrase from Zymomonas mobilis 10232 strongly influence the enzyme activities and products.
abstract: The -1 subsite of bacterial fructansucrases (FSs) (levansucrases and inulosucrases) plays an important role in the substrate recognition, binding and catalysis. Three residues (for example W47, W118 and R193, Zymomonas mobilis levansucrase numbering) at the -1 subsite are completely conserved among FSs. Site-directed mutational analysis showed that the substitutions of the three strictly conserved amino acid residues, W47N, W47H, W118N, W118H, R193K and R193H, significantly decreased enzyme activities and synthesis rates of levan, while the size of the synthesized oligosaccharides had been influenced. These experimental results, combined with 3D structure modeling, lead to our proposal that a single amino acid residue change in subsite -1 of levansucrase can influence change to the size and polarity of the sucrose binding pocket with a concomitant change to substrate binding and catalysis, and thus having an overall influence on the enzyme activities and products.
authors.affiliation: Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, 100081, Beijing, People's Republic of China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Li
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Yan
authors.forename: Zhengfu
authors.initials: Z
authors.lastname: Zhou
authors.forename: Haiying
authors.initials: H
authors.lastname: Yu
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Zhan
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Ping
authors.forename: Min
authors.initials: M
authors.lastname: Lin
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D019943:Amino Acid Substitution / Q000235:genetics*; D002384:Catalysis; D002852:Chromatography, Ion Exchange; D017124:Conserved Sequence / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D006602:Hexosyltransferases / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000235:genetics; D013395:Sucrose / Q000378:metabolism; D017355:Zymomonas / Q000201:enzymology*
chemical_list: D017931:DNA Primers; D013395:Sucrose; D006602:Hexosyltransferases; C021513:levansucrase