Biology subjects
Publications and source records attributed to Giralt-Zuniga, M..
Genomic data on the foodborne pathogen Listeria monocytogenes from Central America are scarse. We analysed 92 isolates collected in Costa Rica over a decade from different regions, compared them to publicly available genomes and identified unnoticed outbreaks. This study calls for mandatory reporting of listeriosis to improve pathogen surveillance.
Both the bacterial flagellum and the evolutionary related injectisome encoded on the Salmonella pathogenicity island 1 (SPI-1) play crucial roles during the infection cycle of Salmonella species. The interplay of both is highlighted by the complex cross-regulation that includes transcriptional control of the flagellar master regulatory operon flhDC by HilD, the master regulator of SPI-1 gene expression. Contrary to the HilD-dependent activation of flagellar gene expression, we report here that activation of HilD resulted in a dramatic loss of motility, which was dependent on the presence of SPI-1. Single cell analyses revealed that HilD-activation results in a SPI-1-dependent induction of the stringent response and a pronounced decrease of proton motive force (PMF), while flagellation was not affected. We further found that activation of HilD enhanced the adhesion of Salmonella to epithelial cells. A transcriptome analysis revealed a concomitant upregulation of several adhesin systems, which when overproduced, phenocopied the HilD-induced motility defect. We propose that a combination of SPI-1-dependent depletion of the PMF and upregulation of adhesins upon HilD-activation allows flagellated Salmonella to rapidly modulate their motility during infection, thereby enabling efficient adhesion to host cells and delivery of effector proteins.