Protein Cofactor Mimics Disrupt Essential Chaperone Function in Stressed Mycobacteria

Tolerance to NSAIDs in Actinobacteria From a Mexican Volcano Crater: Genomics and Bioremediation Potential

Non-steroidal anti-inflammatory drugs (NSAIDs) are emerging contaminants that pose significant health and environmental risks due to their persistence, including their presence in drinking water. Bioremediation, particularly through microorganisms such as actinobacteria, offers a sustainable approach to mitigate these pollutants. Actinobacteria from poly-extreme environments exhibit unique genetic and metabolic adaptations, enabling resistance to and degradation of various contaminants. This study aimed to evaluate the tolerance of actinobacteria to NSAIDs and conduct a genomic analysis of a selected strain. Actinobacteria were isolated from the crater of the Chichonal volcano [Chiapas, Mexico), resulting in 16 isolates. Among these, Micrococcus luteus P8SUE1, Micrococcus yunnanensis P9AGU1, and Kocuria rhizophila P1AGU3 demonstrated tolerance to diclofenac, ibuprofen, and paracetamol at concentrations of 1 ppm, 10 ppm, and 100 ppm, respectively. Whole-genome sequencing of M. yunnanensis P9AGU1 identified genes linked to the degradation of aromatic compounds and adaptations to extreme environmental conditions, highlighting its potential for bioremediation applications.

Lysine succinylome analysis of MRSA reveals critical roles in energy metabolism and virulence

Methicillin-resistant Staphylococcus aureus's (MRSA) resistance poses a global health challenge. This study investigates lysine succinylation in MRSA using proteomics and bioinformatics approaches to uncover metabolic and virulence mechanisms, with the goal of identifying novel therapeutic targets. Mass spectrometry and bioinformatics analyses mapped the MRSA succinylome, identifying 8048 succinylation sites on 1210 proteins. These analyses included Gene Ontology annotation, Kyoto Encyclopedia of Genes and Genomes pathway enrichment, and protein-protein interaction (PPI) network construction (e.g. using the STRING database, a widely used online tool for analyzing protein-protein interactions), providing a comprehensive functional and interactive landscape of succinylated proteins. The succinylated proteins were predominantly involved in cytoplasmic metabolic processes, with enrichment in glycolysis/gluconeogenesis and the tricarboxylic acid cycle. Both of these pathways are critical for MRSA's energy production, growth, and virulence, supplying the necessary metabolic intermediates and energy to support bacterial survival and pathogenicity. Motif analysis revealed 13 conserved motifs, while PPI analysis highlighted fibronectin-binding protein A (FnbA) as a central virulence factor. Succinylation significantly influences MRSA's metabolism and virulence, potentially impacting biofilm by modifying key proteins such as FnbA, bifunctional autolysin, and S-ribosylhomocysteine lyase(LuxS). These findings provide new avenues for developing antibiofilm strategies and therapeutic interventions against MRSA.

HtpG-A Major Virulence Factor and a Promising Vaccine Antigen against Mycobacterium tuberculosis

Tuberculosis (TB) is the leading global cause of death f rom an infectious bacterial agent. Therefore, limiting its epidemic spread is a pressing global health priority. The chaperone-like protein HtpG of M. tuberculosis (Mtb) is a large dimeric and multi-domain protein with a key role in Mtb pathogenesis and promising antigenic properties. This dual role, likely associated with the ability of Heat Shock proteins to act both intra- and extra-cellularly, makes HtpG highly exploitable both for drug and vaccine development. This review aims to gather the latest updates in HtpG structure and biological function, with HtpG operating in conjunction with a large number of chaperone molecules of Mtb. Altogether, these molecules help Mtb recovery after exposure to host-like stress by assisting the whole path of protein folding rescue, from the solubilisation of aggregated proteins to their refolding. Also, we highlight the role of structural biology in the development of safer and more effective subunit antigens. The larger availability of structural information on Mtb antigens and a better understanding of the host immune response to TB infection will aid the acceleration of TB vaccine development.

Bacterial J-Domains with C-Terminal Tags Contact the Substrate Binding Domain of DnaK and Sequester Chaperone Activity

Functional interactions between the molecular chaperone DnaK and cofactor J-proteins (DnaJs), as well as their homologs, are crucial to the maintenance of proteostasis across cell types. In the bacterial pathogen Mycobacterium tuberculosis, DnaK-DnaJ interactions are essential for cell growth and represent potential targets for antibiotic or adjuvant development. While the N-terminal J-domains of J-proteins are known to form important contacts with DnaK, C-terminal domains have varied roles. Here, we have studied the effect of adding C-terminal tags to N-terminal J-domain truncations of mycobacterial DnaJ1 and DnaJ2 to promote additional interactions with DnaK. We found that His6 tags uniquely promote binding to additional sites in the substrate binding domain at the C-terminus of DnaK. Other C-terminal tags attached to J-domains, even peptides known to interact with DnaK, do not produce the same effects. Expression of C-terminally modified DnaJ1 or DnaJ2 J-domains in mycobacterial cells suppresses chaperone activity following proteotoxic stress, which is exaggerated in the presence of a small-molecule DnaK inhibitor. Hence, this work uncovers genetically encodable J-protein variants that may be used to study chaperone-cofactor interactions in other organisms.

Peptide-based molecules for the disruption of bacterial Hsp70 chaperones

DnaK is a chaperone that aids in nascent protein folding and the maintenance of proteome stability across bacteria. Due to the importance of DnaK in cellular proteostasis, there have been efforts to generate molecules that modulate its function. In nature, both protein substrates and antimicrobial peptides interact with DnaK. However, many of these ligands interact with other cellular machinery as well. Recent work has sought to modify these peptide scaffolds to create DnaK-selective and species-specific probes. Others have reported protein domain mimics of interaction partners to disrupt cellular DnaK function and high-throughput screening approaches to discover clinically-relevant peptidomimetics that inhibit DnaK. The described work provides a foundation for the design of new assays and molecules to regulate DnaK activity.