Cooperativity of catalytic and lectin-like domain of Trypanosoma congolense trans-sialidase modulates its catalytic activity

PLoS Negl Trop Dis. 2022 Feb 7;16(2):e0009585. doi: 10.1371/journal.pntd.0009585. eCollection 2022 Feb.

Abstract

Trans-sialidases (TS) represent a multi-gene family of unusual enzymes, which catalyse the transfer of terminal sialic acids (Sia) from sialoglycoconjugates to terminal galactose or N-acetylgalactosamine residues of oligosaccharides without the requirement of CMP-Neu5Ac, the activated Sia used by typical sialyltransferases. Enzymes comprise a N-terminal catalytic domain (CD) followed by a lectin-like domain (LD). Most work on trypanosomal TS has been done on enzymatic activities focusing on the CD of TS from Trypanosoma cruzi (causing Chagas disease in Latin America), subspecies of Trypanosoma brucei, (causing human sleeping sickness in Africa) and Trypanosoma congolense (causing African Animal Trypanosomosis in livestock). Previously, we demonstrated that T. congolense TS (TconTS)-LD binds to several carbohydrates, such as 1,4-β-mannotriose. In this study we investigated the influence of TconTS3-LD on Sia transfer efficiency of TconTS1a-CD by swapping domains. in silico analysis on structure models of TconTS enzymes revealed the potential of domain swaps between TconTS1a and TconTS3 without structural disruptions of the enzymes overall topologies. Recombinant domain swapped TconTS1a/TS3 showed clear Sia transfer activity, when using fetuin and lactose as Sia donor and acceptor substrates, respectively. While Sia transfer activity remained unchanged from the level of TconTS1a, hydrolytic release of free Neu5Ac as a side product was suppressed resulting in increased transfer efficiency. Presence of 1,4-β-mannotriose during TS reactions modulates enzyme activities enhancing transfer efficiency possibly due to occupation of the binding site in TconTS1a-LD. Interestingly this effect was in the same range as that observed when swapping TconTS1a-CD and TconTS3-LD. In summary, this study demonstrate the proof-of-principle for swapping CDs and LDs of TconTS and that TconTS3-LD influences enzymatic activity of TconTS1a-CD providing evidence that LDs play pivotal roles in modulating activities and biological functions of TconTS and possibly other TS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylgalactosamine / metabolism
  • Binding Sites
  • Catalysis
  • Galactose / metabolism
  • Glycoproteins / chemistry*
  • Glycoproteins / genetics
  • Glycoproteins / metabolism*
  • Neuraminidase / chemistry*
  • Neuraminidase / genetics
  • Neuraminidase / metabolism*
  • Oligosaccharides / metabolism
  • Protozoan Proteins / chemistry*
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • Sialic Acids / metabolism
  • Trypanosoma congolense / chemistry
  • Trypanosoma congolense / enzymology*
  • Trypanosoma congolense / genetics

Substances

  • Glycoproteins
  • Oligosaccharides
  • Protozoan Proteins
  • Sialic Acids
  • trans-sialidase
  • Neuraminidase
  • Acetylgalactosamine
  • Galactose

Grants and funding

The financial support of this study was provided by the Deutsche Forschungsgemeinschaft (DFG; https://www.dfg.de), project grants to SK, Ke428/8-1, Ke428/10-1), and by the Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology (ACE-NTDFB; https://acentdfb.abu.edu.ng/facilities). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.