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Tn-seq of Staphylococcus aureus exposed to Calprotectin

ABSTRACT: The host protein calprotectin inhibits the growth of a variety of bacterial pathogens through metal sequestration in a process known as 'nutritional immunity'. Staphylococcus aureus growth is inhibited by calprotectin in vitro and calprotectin is localized in vivo to staphylococcal abscesses during infection. However, the staphylococcal adaptations that provide defense against nutritional immunity and the role of metal-responsive regulators are not fully characterized. In this work, we define the transcriptional response of S. aureus and the role of the metal-responsive regulators, Zur, Fur, and MntR, in response to metal limitation by calprotectin exposure. Additionally, we identified genes affecting the fitness of S. aureus during metal limitation through a Transposon sequencing (Tn-seq) approach. Loss of function mutations in clpP, which encodes a proteolytic subunit of the ATP-dependent Clp protease, demonstrate reduced fitness of S. aureus to the presence of calprotectin. ClpP contributes to pathogenesis in vivo in a calprotectin-dependent manner. These studies establish a critical role for ClpP to combat metal limitation by calprotectin and reveal the genes required for S. aureus to outcompete the host for metals.

ORGANISM(S): Staphylococcus aureus

PROVIDER: GSE266003 | GEO | 2024/05/14

REPOSITORIES: GEO

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Project description:We assessed changes in gene expression in response to manganese availability for the human pathogen Corynebacterium diphtheriae. Total RNA was harvested from wild-type C. diphtheriae strain 1737 and an isogenic ΔmntR (dip0619) grown in semi-defined metal-limited media (mPGT) without or with 5 µM manganese chloride supplementation. Three biological replicates were prepared and five genes were assessed by real-time PCR to validate the array results: dip0124, dip0169, dip0615, dip1923, and dip2261. (Abstract) Corynebacterium diphtheriae is the causative agent of a severe respiratory disease in humans. The bacterial systems required for infection are poorly understood, but the acquisition of metals such as manganese (Mn) are likely critical for host colonization. MntR is a Mn-dependent transcriptional regulator in C. diphtheriae and was previously shown to repress the expression of the mntABCD genes, which encode an ABC metal transporter. However, other targets of Mn and MntR regulation in C. diphtheriae have not been identified. In this study, we use comparisons between the gene expression profiles of wild-type C. diphtheriae strain 1737 grown without or with Mn supplementation and comparisons of gene expression between wild-type and an mntR mutant to characterize the C. diphtheriae Mn and MntR regulon. MntR was observed to both repress and induce the expression of various target genes in a Mn-dependent manner. Genes induced by MntR include the Mn-superoxide dismutase, sodA, and the putative ABC transporter locus, iutABCD. DNA binding studies showed that MntR interacts at the promoter regions for several genes identified in the expression study, and a 17-bp consensus MntR DNA binding site was identified. We found that an mntR mutant displayed increased sensitivity to Mn and Cd that could be alleviated by the additional deletion of the mntA-D transport locus, providing evidence that the MntABCD transporter functions as a Mn uptake system in C. diphtheriae. The findings in this study further our understanding of metal uptake systems and global metal regulatory networks in this important human pathogen.

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Tn-seq of Staphylococcus aureus exposed to Calprotectin

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