4FFI

Crystal Structure of Levan Fructotransferase D54N mutant from Arthrobacter ureafaciens in complex with levanbiose

Summary for 4FFI

• Entry DOI: 10.2210/pdb4ffi/pdb
• Related: 4FFG 4FFH
• Related PRD ID: PRD_900051 PRD_900063
• Descriptor: Levan fructotransferase, beta-D-fructofuranose-(2-6)-beta-D-fructofuranose, beta-D-fructofuranose-(2-6)-beta-D-fructofuranose-(2-6)-beta-D-fructofuranose, ... (4 entities in total)
• Functional Keywords: glycoside hydrolase, transferase
• Biological source: Arthrobacter ureafaciens
• Total number of polymer chains: 4
• Total formula weight: 221136.52

Authors

Park, J.,Rhee, S. (deposition date: 2012-06-01, release date: 2012-07-18, Last modification date: 2024-02-28)

Primary citation

Park, J.,Kim, M.I.,Park, Y.D.,Shin, I.,Cha, J.,Kim, C.H.,Rhee, S.
Structural and functional basis for substrate specificity and catalysis of levan fructotransferase.
J.Biol.Chem., 287:31233-31241, 2012

PubMed Abstract: Levan is β-2,6-linked polymeric fructose and serves as reserve carbohydrate in some plants and microorganisms. Mobilization of fructose is usually mediated by enzymes such as glycoside hydrolase (GH), typically releasing a monosaccharide as a product. The enzyme levan fructotransferase (LFTase) of the GH32 family catalyzes an intramolecular fructosyl transfer reaction and results in production of cyclic difructose dianhydride, thus exhibiting a novel substrate specificity. The mechanism by which LFTase carries out these functions via the structural fold conserved in the GH32 family is unknown. Here, we report the crystal structure of LFTase from Arthrobacter ureafaciens in apo form, as well as in complexes with sucrose and levanbiose, a difructosacchride with a β-2,6-glycosidic linkage. Despite the similarity of its two-domain structure to members of the GH32 family, LFTase contains an active site that accommodates a difructosaccharide using the -1 and -2 subsites. This feature is unique among GH32 proteins and is facilitated by small side chain residues in the loop region of a catalytic β-propeller N-domain, which is conserved in the LFTase family. An additional oligosaccharide-binding site was also characterized in the β-sandwich C-domain, supporting its role in carbohydrate recognition. Together with functional analysis, our data provide a molecular basis for the catalytic mechanism of LFTase and suggest functional variations from other GH32 family proteins, notwithstanding the conserved structural elements.

PubMed: 22810228
DOI: 10.1074/jbc.M112.389270

Experimental method

X-RAY DIFFRACTION (2.3 Å)