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Publication Abstract from PubMed

Typhoid toxin is a virulence factor for the bacterial pathogen Salmonella Typhi, which causes typhoid fever in humans. After its synthesis by intracellular bacteria, typhoid toxin is secreted into the lumen of the Salmonella-containing vacuole by a secretion mechanism strictly dependent on TtsA, a specific muramidase that facilitates toxin transport through the peptidoglycan layer. Here we show that substrate recognition by TtsA depends on a discrete domain within its carboxy terminus, which targets the enzyme to the bacterial poles to recognize YcbB-edited peptidoglycan. Comparison of the atomic structures of TtsA bound to its substrate and that of a close homolog with different specificity identified specific determinants involved in substrate recognition. Combined with structure-guided mutagenesis and in vitro and in vivo crosslinking experiments, this study provides an unprecedented view of the mechanisms by which a muramidase recognizes its peptidoglycan substrate to facilitate protein secretion.

Mechanisms of substrate recognition by a typhoid toxin secretion-associated muramidase.,Geiger T, Lara-Tejero M, Xiong Y, Galan JE Elife. 2020 Jan 20;9. pii: 53473. doi: 10.7554/eLife.53473. PMID:31958059^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.