Moraxella catarrhalis Lgt2, a galactosyltransferase with broad acceptor substrate specificity

Area of Science:

• Microbiology
• Glycobiology
• Bacterial Pathogenesis

Background:

• Lipo-oligosaccharide (LOS) biosynthesis in Moraxella catarrhalis is genetically understood, with proposed roles for its glycosyltransferases.
• Identifying the specific functions of these enzymes is key to understanding M. catarrhalis virulence and potential therapeutic targets.

Purpose of the Study:

• To express and characterize the putative galactosyltransferase Lgt2(B/C) from Moraxella catarrhalis.
• To determine the enzymatic properties, including pH optimum, temperature optimum, donor/acceptor specificity, and cofactor requirements of Lgt2(B/C).

Main Methods:

• Amplification and expression of the lgt2(B/C) gene in Escherichia coli.
• Purification of the recombinant Lgt2(B/C) enzyme.
• Enzymatic assays to determine catalytic activity, pH/temperature optima, and substrate specificity.

Main Results:

• The Lgt2(B/C) enzyme was successfully expressed and purified.
• Catalytic activity assays revealed optimal function at specific pH and temperature ranges.
• Lgt2(B/C) demonstrated galactosyltransferase activity with broad acceptor specificity, requiring exogenous Mg(2+) for optimal performance.

Conclusions:

• Lgt2(B/C) is confirmed as a galactosyltransferase involved in M. catarrhalis LOS biosynthesis.
• The enzyme's characterized properties provide insights into the glycosylation pathway.
• Understanding Lgt2(B/C) function contributes to the broader knowledge of bacterial glycoconjugate synthesis and potential drug targets.