Molecular cloning, characterisation and molecular modelling of two novel T-synthases from mollusc origin

TL;DR

Researchers cloned and characterized two new T-synthase enzymes from molluscs, revealing insights into their structure and function.

Contribution

The study identifies and characterizes novel T-synthases from molluscs, including one lacking a previously essential consensus sequence.

Findings

T-synthases from Pomacea canaliculata and Crassostrea gigas were cloned and shown to have core 1 β1,3-galactosyltransferase activity.

The T-synthase from P. canaliculata lacks the CCSD consensus sequence previously thought essential.

Both enzymes exhibit similar biochemical parameters to known T-synthases from other species.

Abstract

The glycoprotein-N-acetylgalactosamine β1,3-galactosyltransferase, known as T-synthase (EC 2.4.1.122), plays a crucial role in the synthesis of the T-antigen, which is the core 1 O-glycan structure. This enzyme transfers galactose from UDP-Gal to GalNAc-Ser/Thr. The T-antigen has significant functions in animal development, immune response, and recognition processes. Molluscs are a successful group of animals that inhabit various environments, such as freshwater, marine, and terrestrial habitats. They serve important roles in ecosystems as filter feeders and decomposers but can also be pests in agriculture and intermediate hosts for human and cattle parasites. The identification and characterization of novel carbohydrate active enzymes, such as T-synthase, can aid in the understanding of molluscan glycosylation abilities and their adaptation and survival abilities. Here, the T-synthase enzymes from the snail Pomacea canaliculata and the oyster Crassostrea gigas are identified, cloned, expressed, and characterized, with a focus on structural elucidation. The synthesized enzymes display core 1 β1,3-galactosyltransferase activity using pNP-α-GalNAc as substrate and exhibit similar biochemical parameters as previously characterised T-synthases from other species. While the enzyme from C. gigas shares the same structural parameters with the other enzymes characterised so far, the T-synthase from P. canaliculata lacks the consensus sequence CCSD, which was previously considered indispensable.

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