Biology subjects

Bengoechea, J.

Publications and source records attributed to Bengoechea, J..

3 recordsLinked to original sources

bioRxiv2025

Klebsiella pneumoniae remodels its Kdo2-lipid A in a TLR4-dependent manner to adapt to the macrophage intracellular environment

Pathogen adaptations to the intracellular macrophage environment remain poorly understood. We performed a high-resolution structural analysis of the lipid A purified from intracellular Klebsiella pneumoniae (KP). In both mouse and human macrophages, KP produces hexa- and hepta-acylated lipid A species modified with palmitate and 2-hydroxylated. LpxL1, PagP, and LpxO enzymes govern the intracellular lipid A in a PhoPQ-dependent manner triggered by the acidic pH of the KP-containing vacuole (KCV). Absence of LpxO and PagP lipid A modifications impairs intracellular survival and heightens NF-{kappa}B and IRF3-mediated inflammation, though KCV maturation remains unaffected. Instead, these modifications fortify the bacterial membrane. Absence of TLR4-TRAM-TRIF signalling increases KCV pH, impairing the production of the intracellular lipid A. KP intracellular survival is reduced in tlr4-/- macrophages, highlighting the critical role of this signalling pathway in KP immune evasion and how the pathogen has evolved to rely on innate immune system cues for virulence.

microbiology↗

bioRxiv2025

Klebsiella pneumoniae disrupts vasodilation by targeting eNOS post translational modifications via the type VI secretion system and the capsule polysaccharide

Vasodilation is a crucial protective response to inflammation and infection. Endothelial cells control vasodilation through the bioavailability of eNOS-produced nitric oxide (NO), and the generation of endothelium-dependent hyperpolarization (EDH). Here, we demonstrate that Klebsiella pneumoniae, one of the most prevalent blood stream infection pathogens, inhibits agonist-induced vasodilation by blunting the NO-dependent pathway and attenuating the EDH pathway. The type VI secretion system (T6SS) effector VgrG4 licences the kinase PKC{beta} in an NLRX1-controlled mitochondria reactive oxygen species (mtROS)-dependent manner to phosphorylate the eNOS inhibitory site Thr495, effectively dampening eNOS activity. The capsule polysaccharide, on the other hand, limits the phosphorylation of the eNOS activation site Ser1177 by inducing the phosphatase PP2Ac upon activation of an EGF receptor-dependent pathway. VgrG4-induced mtROS attenuates the EDH pathway. Overall, this work reveals a new anti-host activity of the T6SS and illustrates how pathogens can control vascular biology by targeting eNOS post translational modifications.

microbiology↗

bioRxiv2022

A gas phase fractionation acquisition scheme integrating ion mobility for rapid diaPASEF library generation

Data independent acquisition (DIA or DIA/SWATH) mass spectrometry has emerged as a primary measurement strategy in the field of quantitative proteomics. diaPASEF is a recent adaptation that leverages trapped ion mobility spectrometry (TIMS) to improve selectivity and increase sensitivity. The complex fragmentation spectra generated by co-isolation of peptides in DIA mode are most typically analyzed with reference to prior knowledge in the form of spectral libraries. The best-established method for generating libraries uses data dependent acquisition (DDA) mode, or DIA mode if appropriately deconvoluted, often including offline fractionation to increase depth of coverage. More recently strategies for spectral library generation based on gas phase fractionation (GPF), where a representative sample is injected serially using narrow DIA windows that cover different mass ranges of the complete precursor space, have been introduced that performed comparably to deep offline fractionation-based libraries for DIA data analysis. Here, we investigated whether an analogous GPF-based library building approach that accounts for the ion mobility (IM) dimension is useful for the analysis of diaPASEF data and can remove the need for offline fractionation. To enable a rapid library development approach for diaPASEF we designed a GPF acquisition scheme covering the majority of multiply charged precursors in the m/z vs 1/K0 space requiring 7 injections of a representative sample and compared this with libraries generated by direct deconvolution-based analysis of diaPASEF data or by deep offline fractionation and ddaPASEF. We found that library generation by IM-GPF outperformed direct deconvolution of the diaPASEF data and had performance approaching that of a deep offline fractionation library, when analysing diaPASEF data. This establishes the ion mobility integrated GPF scheme as a pragmatic approach to rapid library generation for the analysis of diaPASEF data.

systems biology↗