Biology subjects

Klepsch, M.

Publications and source records attributed to Klepsch, M..

3 recordsLinked to original sources

bioRxiv2025

Metabolic role of the LutACB operon in Neisseria gonorrhoeae resistance to neutrophil-mediated clearance

Neisseria gonorrhoeae, an obligate human pathogen, causes the sexually transmitted disease gonorrhoea and primarily colonizes the human genitourinary tract. An infection triggers a strong neutrophil-driven inflammatory response; however, viable gonococci are frequently recovered from neutrophil-rich patient exudates, indicating that these pathogens can survive neutrophil-mediated killing in vivo. To identify bacterial factors involved in this interaction, we screened a N. gonorrhoeae transposon library for mutants with reduced survival in polymorphonuclear leukocytes (PMNs). Among the identified candidates was NGFG_RS05085 (lutB), encoding an L-lactate oxidation FeS protein within the LutACB operon, which includes lutA (NGFG_RS05075), an FeS-binding protein, and lutC, the lactate utilisation protein C, (NGFG_RS05080). Deletion of lutA, lutB, or lutC did not significantly impair growth in standard culture medium or in minimal medium complemented with glucose, L-Lactate, or pyruvate. lutB and lutC, but not lutA, knockout significantly reduced bacterial survival within neutrophils compared to the wild-type strain. Polar effects of the mutations were ruled out by monitoring gene expression in deletion mutants. Metabolic profiling revealed disruption in nucleotide and glutathione synthesis, connecting the LutACB operon with sulfur metabolism, which could be required for a defence against neutrophil-derived reactive oxygen species (ROS). These findings highlight the important novel role of the LutACB operon, which connects lactate utilization and sulfur metabolism, and enables N. gonorrhoeae to withstand neutrophil-mediated oxidative stress during infection.

microbiology↗

bioRxiv2022

A central role of sibling sRNAs NgncR_162/163 in main metabolic pathways of Neisseria gonorrhoeae

Bacterial regulatory RNAs (sRNAs) have been implicated in the regulation of numerous metabolic pathways. In most of these studies, sRNA-dependent regulation of mRNAs or proteins of enzymes in metabolic pathways has been predicted to affect the metabolism of these bacteria. However, only in very few cases has the role in metabolism been demonstrated. We performed here a combined transcriptome and metabolome analysis to define the regulon of the sibling sRNAs NgncR_162 and NgncR_163 and their impact on the metabolism of the major human pathogen Neisseria gonorrhoeae. These sRNA have previously been shown to control genes of the citric acid and methylcitrate cycle by post-transcriptional negative regulation. By transcriptome analysis we expand the NgncR_162/163 regulon by several new members and provide evidence that the sibling sRNAs act as both negative and positive regulators of target gene expression. Newly identified NgncR_162/163 targets are mostly involved in transport processes, especially the uptake of glycine, branched chain amino acids and phenylalanine. NgncR_162/163 also play key roles in the control of serine-glycine metabolism and hence probably affect biosynthesis of nucleotides, vitamins and other amino acids via the supply of C1-units. Metabolic flux analysis demonstrated a bipartite metabolism with glucose degradation providing intermediates for anabolic pathways, while energy metabolism via the citric acid cycle is mainly driven by amino acids, which feed into the cycle. Thus, by combined RNA-seq and metabolomics we significantly extended the regulon of NgncR_162/163 and demonstrate their role in the regulation of central metabolic pathways of the gonococcus. ImportanceNeisseria gonorrhoeae is a major human pathogen which infects more than 100 million people every year. An alarming development is the emergence of gonococcal strains resistant against virtually all of the antibiotics used for their treatment. Despite the medical importance and the vanishing treatment options of gonococcal infections, the bacterial metabolism and its regulation is only ill defined until today. We investigate here the regulation of the gonococcal metabolism by two previously studied sRNAs, NgncR_162/163 using RNA-seq and metabolomics. The results provided in this study demonstrate the regulation of transport processes and metabolic pathways involved in the biosynthesis of nucleotides, vitamins and amino acids by NgncR_162/163. Combined transcriptome and metabolome analyses provide a thus far unreached depth in the regulation of metabolic pathways by the neisserial sibling sRNAs and may therefore also be suitable for functional analysis of a growing number of other bacterial metabolic sRNA regulators.

microbiology↗

bioRxiv2020

Identification of a novel LysR-type transcriptional regulator in Staphylococcus aureus that is crucial for secondary tissue colonization during metastatic bloodstream infection

Staphylococcus aureus is a common cause of bacteremia that can lead to severe complications once the bacteria exit the bloodstream and establish infection into secondary organs. Despite its clinical relevance, little is known about the bacterial factors facilitating the development of these metastatic infections. Here, we used a S. aureus transposon mutant library coupled to transposon insertion sequencing (Tn-Seq) to identify genes that are critical for efficient bacterial colonization of secondary organs in a murine model of metastatic bloodstream infection. Our transposon screen identified a LysR-type transcriptional regulator (LTTR), which was required for efficient colonization of secondary organs such as the kidneys in infected mice. The critical role of LTTR in secondary organ colonization was confirmed using an isogenic mutant deficient in the expression of LTTR. To identify the set of genes controlled by LTTR, we used a S. aureus strain carrying the LTTR gene in an inducible expression plasmid. Gene expression analysis upon induction of LTTR showed increased transcription of genes involved in branched chain amino-acid biosynthesis, a methionine sulfoxide reductase and a copper transporter as wells as decreased transcription of genes coding for urease and components of pyrimidine nucleotides. Furthermore, we show that transcription of LTTR is repressed by glucose, induced under microaerobic conditions, and required trace amounts of copper ions. Our data thus pinpoints LTTR as an important element that enable a rapid adaptation of S. aureus to the changing host microenvironment.

microbiology↗