A novel phospholipase A2 is a core component of the typhoid toxin genetic islet.

Autor:	Gartly SC; Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada., Barretto LAF; Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada., Côté AMT; Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada., Kosowan ZA; Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada., Fowler CC; Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada. Electronic address: cfowler@ualberta.ca.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2024 Oct; Vol. 300 (10), pp. 107758. Date of Electronic Publication: 2024 Sep 12.
DOI:	10.1016/j.jbc.2024.107758
Abstrakt:	Salmonella Typhi, the cause of typhoid fever, is a bacterial pathogen of substantial global importance. Typhoid toxin is a secreted AB-type toxin that is a key S. Typhi virulence factor encoded within a 5-gene genetic islet. Four genes in this islet have well-defined roles in typhoid toxin biology; however, the function of the fifth gene is unknown. Here, we investigate the function of this gene, which we name ttaP. We show that ttaP is cotranscribed with the typhoid toxin subunit cdtB, and we perform genomic analyses that indicate that TtaP is very highly conserved in typhoid toxin islets found in diverse salmonellae. We show that TtaP is a distant homolog of group XIV secreted phospholipase A2 (PLA2) enzymes, and experimentally demonstrate that TtaP is a bona fide PLA2. Sequence and structural analyses indicate that TtaP differs substantially from characterized PLA2s, and thus represents a novel class of PLA2. Secretion assays revealed that TtaP is neither cosecreted with typhoid toxin, nor is it required for toxin secretion. Although TtaP is a phospholipase that remains associated with the S. Typhi cell, assays that probed for altered cell envelope integrity failed to identify any differences between WT S. Typhi and a ttaP deletion strain. Collectively, this study identifies a biochemical activity for the lone uncharacterized typhoid toxin islet gene and lays the groundwork for exploring how this gene factors into S. Typhi pathogenesis. This study further identifies a novel class of PLA2, enzymes that have a wide range of industrial applications. Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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