Zinc limitation in Klebsiella pneumoniae profiled by quantitative proteomics influences transcriptional regulation and cation transporter-associated capsule production

Abstract

Background Microbial organisms encounter a variety of environmental conditions, including changes to metal ion availability. Metal ions play an important role in many biological processes for growth and survival. As such, microbes alter their cellular protein levels and secretion patterns in adaptation to a changing environment. This study focuses on Klebsiella pneumoniae, an opportunistic bacterium responsible for nosocomial infections. By using K. pneumoniae, we aim to determine how a nutrient-limited environment (e.g., zinc depletion) modulates the cellular proteome and secretome of the bacterium. By testing virulence in vitro, we provide novel insight into bacterial responses to limited environments in the presence of the host. Results Analysis of intra- and extracellular changes identified 2380 proteins from the total cellular proteome (cell pellet) and 246 secreted proteins (supernatant). Specifically, HutC, a repressor of the histidine utilization operon, showed significantly increased abundance under zinc-replete conditions, which coincided with an expected reduction in expression of genes within the hut operon from our validating qRT-PCR analysis. Additionally, we characterized a putative cation transport regulator, ChaB that showed significantly higher abundance under zinc-replete vs. -limited conditions, suggesting a role in metal ion homeostasis. Phenotypic analysis of a chaB deletion strain demonstrated a reduction in capsule production, zinc-dependent growth and ion utilization, and reduced virulence when compared to the wild-type strain. Conclusions This is first study to comprehensively profile the impact of zinc availability on the proteome and secretome of K. pneumoniae and uncover a novel connection between zinc transport and capsule production in the bacterial system.

Cross-Kingdom Infection of Macrophages Reveals Pathogen- and Immune-Specific Global Reprogramming and Adaptation

“…Furthermore, our observation of fungus-driven bacterial responses to infection defined a role for enhanced nutrient acquisition (i.e., TonB-dependent outer membrane siderophore receptor, a putative receptor, the iron uptake system component isochorismatase, and outer membrane porin) in the presence of C. neoformans . These findings were anticipated given the competition for nutrients by K. pneumoniae and C. neoformans within nutrient-limited environments ( 40 , 46 , 47 ). Furthermore, we observed regulation of signaling networks (i.e., adenylate kinase), metabolism (i.e., ATP phosphoribosyltransferase, aminotransferase, phosphoserine aminotransferase), and translation (i.e., 50S ribosomal protein), which support global changes to bacterial protein production driven by the presence of an established fungal infection.…”

Label‐free quantitative proteomics identifies unique proteomes of clinical isolates of the Liverpool Epidemic Strain of Pseudomonas aeruginosa and laboratory strain PAO1

“…Samples were prepared for mass spectrometry following previously described protocols [26,27]. Lysis buffer was prepared by adding one complete, Mini, EDTA‐free Protease Inhibitor Cocktail tablet (Roche) to 10 mL 0.1 M Tris‐HCl, pH 8.5.…”

Interactions and Implications of Klebsiella pneumoniae with Human Immune Responses and Metabolic Pathways: A Comprehensive Review

“…Notably, K. pneumoniae has the capacity to modulate the degradation of specific amino acids, such as histidine. 38 This interplay bears significant implications for both the host’s immune response dynamics and the pathogen’s viability within the host environment. 39 However, The specific mechanisms underlying this interaction, particularly its impact on the overall outcome of K. pneumoniae infections, warrant further comprehensive investigation.…”