Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2021

Bacterial toxins: Glycans, proteins and novel applications.... (#5)

Christopher Day 1
  1. Institute for Glycomics, Griffith University, Southport, QLD, Australia

I have worked with a range of collaborators to solve the glycan and/or protein binding from a range of toxin families including cholesterol dependent cytolysins (CDCs), AB5 toxins and leukocidins.

In this broad ranging program I have worked with Lucy Shewell, Mike Jennings, James Paton and Mark Walker to solve the carbohydrate receptors of eight CDCs (1) and a shared protein target for the CDCs pneumolysin (Ply) and StreptolysinO (SLO).

The protein targeting of the CDCs was further enabled by Victor Torres (NYU) as we collaborated on the host target identification of the leukocidinAB. LukAB had high affinity binding to the I-domain of the human integrin protein CD11b (2). While investigating the affinity for LukAB mutants (3) for the I-domain of CD11b, I was also screening CDCs against another target and happened to discover by chance the high affinity binding of Ply and SLO to CD11b. The binding of SLO to CD11b is remarkably similar to that of LukAB, recognizing the same region and also having human specificity. Ply bound in a very different manner recognizing the I-domain in a region that is glycosylated in the native receptor, a glycosylation site that typically contains a terminal sialyl-Lewis X motif that is preferred by Ply (1).

An unexpected outcome from toxin analysis came with work on the toxin SubB in collaboration with the Paton's, Mike Jennings and Lucy Shewell. SubB was already known to be quite specific for the non-human produced sugar N-Glycolylneuraminic acid (Neu5Gc), however, it only recognized certain linkages and still bound to N-Acetylneuraminic acid (Neu5Ac). Neu5Gc is a well recognized cancer marker and was being investigated as a potential diagnostic by several groups. By reengineering SubB to SubB2M we developed a hugely specific and sensitive protein that can recognize a pan cancer marker (4,5,6).

Through the study of toxins I have increased the knowledge of host targets and helped to create a novel application for a bacterial toxin.

  1. Shewell LK, Day CJ, Jen FE, Haselhorst T, Atack JM, Reijneveld JF, Everest-Dass A, James DBA, Boguslawski KM, Brouwer S, Gillen CM, Luo Z, Kobe B, Nizet V, von Itzstein M, Walker MJ, Paton AW, Paton JC, Torres VJ, Jennings MP. All major cholesterol-dependent cytolysins use glycans as cellular receptors. Sci Adv. 2020 May 22;6(21):eaaz4926.
  2. DuMont AL, Yoong P, Day CJ, Alonzo F 3rd, McDonald WH, Jennings MP, Torres VJ. Staphylococcus aureus LukAB cytotoxin kills human neutrophils by targeting the CD11b subunit of the integrin Mac-1. Proc Natl Acad Sci U S A. 2013 Jun 25;110(26):10794-9.
  3. DuMont AL, Yoong P, Liu X, Day CJ, Chumbler NM, James DB, Alonzo F 3rd, Bode NJ, Lacy DB, Jennings MP, Torres VJ. Identification of a crucial residue required for Staphylococcus aureus LukAB cytotoxicity and receptor recognition. Infect Immun. 2014 Mar;82(3):1268-76.
  4. Day CJ, Paton AW, Higgins MA, Shewell LK, Jen FE, Schulz BL, Herdman BP, Paton JC, Jennings MP. Structure aided design of a Neu5Gc specific lectin. Sci Rep. 2017 May 4;7(1):1495.
  5. Wang J, Shewell LK, Paton AW, Paton JC, Day CJ, Jennings MP. Specificity and utility of SubB2M, a new N-glycolylneuraminic acid lectin. Biochem Biophys Res Commun. 2018 Jun 7;500(3):765-771.
  6. Shewell LK, Wang JJ, Paton JC, Paton AW, Day CJ, Jennings MP. Detection of N-glycolylneuraminic acid biomarkers in sera from patients with ovarian cancer using an engineered N-glycolylneuraminic acid-specific lectin SubB2M. Biochem Biophys Res Commun. 2018 Dec 9;507(1-4):173-177.