Báo cáo khoa học: Crystal structures of the apo form of b-fructofuranosidase from Bifidobacterium

Crystal structures of the apo form of b-fructofuranosidase

from Bifidobacterium longum and its complex with

fructose

Anna Bujacz, Marzena Jedrzejczak-Krzepkowska, Stanislaw Bielecki, Izabela Redzynia and

Grzegorz Bujacz

Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Technical University of Lodz, Poland

Introduction

Bifidobacteria are found in human and animal gastro￾intestinal tracts, as well as in the oral cavity and the

vagina [1]. They are among the first bacteria that colo￾nize the sterile digestive system of newborns and they

become predominant micro-organisms ( 95% of the

colonic flora) in breast-fed infants [2].

In infants, the most frequently detected bifidobacteria

species are Bifidobacterium breve, Bifidobacterium infan￾tis, Bifidobacterium bifidum and Bifidobacterium longum.

The latter one also inhabits the intestines of adults,

despite the fact that the composition of bifidobacterial

species changes and the amount of bifidobacteria

decreases with age [3–6]. They are Gram-positive, nons￾porulating and nonmotile rods, classified as lactic acid

bacteria, due to their ability to anaerobically ferment

carbohydrates [7,8]. These bacteria are known as micro￾Keywords

b-fructofuranosidase;

Bifidobacterium longum; crystal structure;

glycoside hydrolase family GH32; lactic acid

bacteria

Correspondence

A. Bujacz, Institute of Technical

Biochemistry, Faculty of Biotechnology and

Food Sciences, Technical University of Lodz,

Stefanowskiego 4 ⁄ 10, 90-924 Lodz, Poland

Fax: 48 42 6366618

Tel: 48 42 6313494

E-mail: [email protected]

(Received 13 January 2011, revised 25

February 2011, accepted 15 March 2011)

doi:10.1111/j.1742-4658.2011.08098.x

We solved the 1.8 A˚ crystal structure of b-fructofuranosidase from Bifido￾bacterium longum KN29.1 – a unique enzyme that allows these probiotic

bacteria to function in the human digestive system. The sequence of b-fruc￾tofuranosidase classifies it as belonging to the glycoside hydrolase family

32 (GH32). GH32 enzymes show a wide range of substrate specificity and

different functions in various organisms. All enzymes from this family

share a similar fold, containing two domains: an N-terminal five-bladed

b-propeller and a C-terminal b-sandwich module. The active site is located

in the centre of the b-propeller domain, in the bottom of a ‘funnel’. The

binding site, )1, responsible for tight fructose binding, is highly conserved

among the GH32 enzymes. Bifidobacterium longum KN29.1 b-fructofura￾nosidase has a 35-residue elongation of the N-terminus containing a five￾turn a-helix, which distinguishes it from the other known members of the

GH32 family. This new structural element could be one of the functional

modifications of the enzyme that allows the bacteria to act in a human

digestive system. We also solved the 1.8 A˚ crystal structure of the b-fruc￾tofuranosidase complex with b-D-fructose, a hydrolysis product obtained

by soaking apo crystal in raffinose.

Database

Coordinates and structure factors have been deposited in the Protein Data Bank under acces￾sion codes: 3PIG and 3PIJ

Structured digital abstract

l b-fructofuranosidase binds to b-fructofuranosidase by x-ray crystallography (View interaction)

Abbreviation

GH32, glycoside hydrolase family 32.

1728 FEBS Journal 278 (2011) 1728–1744 ª 2011 The Authors Journal compilation ª 2011 FEBS