The crystal structure of Thermotoga maritima maltosyltransferase and its implications for the molecular basis of the novel transfer specificity 1 1Edited by R. Huber

134

Background: GlgE is a maltosyltransferase involved in bacterial ␣-glucan biosynthesis and is a genetically validated antituberculosis target. Results: We have determined the catalytic properties of Streptomyces coelicolor GlgE and solved its structure. Conclusion:The enzyme has the same catalytic properties as Mycobacterium tuberculosis GlgE and the structure reveals how GlgE functions. Significance: The structure will help guide the development of inhibitors with therapeutic potential.

Section: Discussionmentioning

confidence: 87%

Structure of Streptomyces Maltosyltransferase GlgE, a Homologue of a Genetically Validated Anti-tuberculosis Target

Syson

Stevenson

Rejzek

et al. 2011

134

“…This N-terminal ␤ region has a low degree of structural similarity to Thermoactinomyces vulgaris R-47 ␣-amylase II (Protein Data Bank code 1BVZ) (43), T. maritima maltosyltransferase (Protein Data Bank code 1GJU) (44), and bovine lysosomal ␣-mannosidase (Protein Data Bank code 1O7D) (45), but the function of the N-terminal region remains unclear.…”

Section: Resultsmentioning

confidence: 99%

Structural Basis of the Catalytic Reaction Mechanism of Novel 1,2-α-L-Fucosidase from Bifidobacterium bifidum

Nagae

Tsuchiya

Katayama

et al. 2007

118

101

1,2-␣-L-Fucosidase (AfcA), which hydrolyzes the glycosidic linkage of Fuc␣1-2Gal via an inverting mechanism, was recently isolated from Bifidobacterium bifidum and classified as the first member of the novel glycoside hydrolase family 95. To better understand the molecular mechanism of this enzyme, we determined the x-ray crystal structures of the AfcA catalytic (Fuc) domain in unliganded and complexed forms with deoxyfuconojirimycin (inhibitor), 2-fucosyllactose (substrate), and L-fucose and lactose (products) at 1.12-2.10 Å resolution. The AfcA Fuc domain is composed of four regions, an N-terminal ␤ region, a helical linker, an (␣/␣) 6 helical barrel domain, and a C-terminal ␤ region, and this arrangement is similar to bacterial phosphorylases. In the complex structures, the ligands were buried in the central cavity of the helical barrel domain. Structural analyses in combination with mutational experiments revealed that the highly conserved Glu 566 probably acts as a general acid catalyst. However, no carboxylic acid residue is found at the appropriate position for a general base catalyst. Instead, a water molecule stabilized by Asn 423 in the substrate-bound complex is suitably located to perform a nucleophilic attack on the C1 atom of L-fucose moiety in 2-fucosyllactose, and its location is nearly identical near the O1 atom of ␤-L-fucose in the products-bound complex. Based on these data, we propose and discuss a novel catalytic reaction mechanism of AfcA.

“…The bacterial amylomaltases are structurally and functionally related to the plant disproportionating enzymes ("D-enzymes") of GH77, which transfer maltosyl and longer 4-␣-glucanosyl units from maltotriose and higher congeners (9). Likewise, certain thermophilic bacterial 4-␣-glucanotransferases of GH13 catalyze the disproportionation of maltotriose (10,11), maltotetraose (12,13), and longer 4-␣-glucan chains.…”

mentioning

confidence: 99%

Structural Enzymology of Cellvibrio japonicus Agd31B Protein Reveals α-Transglucosylase Activity in Glycoside Hydrolase Family 31

Larsbrink

Izumi

Hemsworth

et al. 2012

Background:Transglycosylases are important enzymes in bacterial glycogen metabolism. Results:The tertiary structure and function of a novel ␣-transglucosylase have been defined. Conclusion: In addition to previously known activities, glycoside hydrolase family 31 (GH31) contains a group of enzymes with 1,4-␣-glucan 4-␣-glucosyltransferase activity. Significance: This gives new insight into bacterial glycogen utilization and will inform future bioinformatics analyses of (meta)genomes.