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Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility
Published on: March 11, 2022
Glycosyltransferase complexes improve glycolipid synthesis.
Waldo Spessott1, Pilar M Crespo, José Luis Daniotti
1Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC, UNC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000 HUA Córdoba, Argentina.
FEBS Letters
|June 13, 2012
Summary
Sialic acid addition by Sial-T2 activates Sial-T1 in CHO-K1 cells. This activation of lactosylceramide (LacCer) metabolism by Sial-T1 is linked to a multienzyme complex, enhancing ganglioside synthesis.
Area of Science:
- Glycobiology
- Cell Biology
- Biochemistry
Background:
- Ganglioside synthesis involves sequential sialic acid addition to lactosylceramide (LacCer).
- Sialyltransferases Sial-T1 and Sial-T2 catalyze these steps, with CHO-K1 cells lacking Sial-T2 and producing only GM3.
Purpose of the Study:
- To investigate the mechanism behind the apparent activation of Sial-T1 in CHO-K1 cells expressing Sial-T2.
- To understand the role of Sial-T2 in regulating Sial-T1 activity and ganglioside biosynthesis.
Main Methods:
- Transfection of CHO-K1 cells with Sial-T2.
- Enzyme activity assays on cell homogenates.
- Analysis of Sial-T1 activation in response to Sial-T2 expression and functional domains.
Main Results:
- Sial-T1 activity was approximately 2.5-fold higher in CHO-K1 cells expressing Sial-T2 compared to untransfected cells.
- Sial-T1 activation was not due to increased enzyme levels, gene transcription, or protein stabilization.
- A catalytically inactive Sial-T2 mutant did not induce Sial-T1 activation.
- Sial-T1 activation was linked to the formation of a multienzyme complex involving Gal-T1, Sial-T1, and Sial-T2.
Conclusions:
- Sial-T2's enzymatic activity within a multienzyme complex is crucial for apparent Sial-T1 activation.
- The proposed mechanism involves Sial-T2 converting GM3 to GD3 and GT3, freeing Sial-T1 for subsequent LacCer processing and enhancing overall ganglioside synthesis.
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