Cell response of Escherichia coli to cisplatin-induced stress

Isolate Specific Cold Response of Yersinia enterocolitica in Transcriptional, Proteomic, and Membrane Physiological Changes

Yersinia enterocolitica, a zoonotic foodborne pathogen, is able to withstand low temperatures. This psychrotrophic ability allows it to multiply in food stored in refrigerators. However, little is known about the Y. enterocolitica cold response. In this study, isolate-specific behavior at 4°C was demonstrated and the cold response was investigated by examining changes in phenotype, gene expression, and the proteome. Altered expression of cold-responsive genes showed that the ability to survive at low temperature depends on the capacity to acclimate and adapt to cold stress. This cold acclimation at the transcriptional level involves the transient induction and effective repression of cold-shock protein (Csp) genes. Moreover, the resumption of expression of genes encoding other non-Csp is essential during prolonged adaptation. Based on proteomic analyses, the predominant functional categories of cold-responsive proteins are associated with protein synthesis, cell membrane structure, and cell motility. In addition, changes in membrane fluidity and motility were shown to be important in the cold response of Y. enterocolitica. Isolate-specific differences in the transcription of membrane fluidity- and motility-related genes provided evidence to classify strains within a spectrum of cold response. The combination of different approaches has permitted the systematic description of the Y. enterocolitica cold response and gives a better understanding of the physiological processes underlying this phenomenon.

Shotgun proteomic analysis of nanoparticle-synthesizing Desulfovibrio alaskensis in response to platinum and palladium

Platinum and palladium are much sought-after metals of critical global importance in terms of abundance and availability. At the nano-scale these metals are of even higher value due to their catalytic abilities for industrial applications. Desulfovibrio alaskensis is able to capture ionic forms of both of these metals, reduce them and synthesize elemental nanoparticles. Despite this ability, very little is known about the biological pathways involved in the formation of these nanoparticles. Proteomic analysis of D. alaskensis in response to platinum and palladium has highlighted those proteins involved in both the reductive pathways and the wider stress-response system. A core set of 13 proteins was found in both treatments and consisted of proteins involved in metal transport and reduction. There were also seven proteins that were specific to either platinum or palladium. Overexpression of one of these platinum-specific genes, a NiFe hydrogenase small subunit (Dde_2137), resulted in the formation of larger nanoparticles. This study improves our understanding of the pathways involved in the metal resistance mechanism of Desulfovibrio and is informative regarding how we can tailor the bacterium for nanoparticle production, enhancing its application as a bioremediation tool and as a way to capture contaminant metals from the environment.

Amino acid-linked platinum(II) compounds: non-canonical nucleoside preferences and influence on glycosidic bond stabilities

Abstract

Nucleobases serve as ideal targets where drugs bind and exert their anticancer activities. Cisplatin (cisPt) preferentially coordinates to 2′-deoxyguanosine (dGuo) residues within DNA. The dGuo adducts that are formed alter the DNA structure, contributing to inhibition of function and ultimately cancer cell death. Despite its success as an anticancer drug, cisPt has a number of drawbacks that reduce its efficacy, including repair of adducts and drug resistance. Some approaches to overcome this problem involve development of compounds that coordinate to other purine nucleobases, including those found in RNA. In this work, amino acid-linked platinum(II) (AAPt) compounds of alanine and ornithine (AlaPt and OrnPt, respectively) were studied. Their reactivity preferences for DNA and RNA purine nucleosides (i.e., 2′-deoxyadenosine (dAdo), adenosine (Ado), dGuo, and guanosine (Guo)) were determined. The chosen compounds form predominantly monofunctional adducts by reacting at the N1, N3, or N7 positions of purine nucleobases. In addition, features of AAPt compounds that impact the glycosidic bond stability of Ado residues were explored. The glycosidic bond cleavage is activated differentially for AlaPt-Ado and OrnPt-Ado isomers. Formation of unique adducts at non-canonical residues and subsequent destabilization of the glycosidic bonds are important features that could circumvent platinum-based drug resistance.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00775-019-01693-y) contains supplementary material, which is available to authorized users.

Repurposing the anticancer drug cisplatin with the aim of developing novel Pseudomonas aeruginosa infection control agents

Antibiotic resistance threatens effective treatment of microbial infections globally. This situation has spurred the hunt for new antimicrobial compounds in both academia and the pharmaceutical industry. Here, we report how the widely used antitumor drug cisplatin may be repurposed as an effective antimicrobial against the nosocomial pathogen Pseudomonas aeruginosa. Cisplatin was found to effectively kill strains of P. aeruginosa. In such experiments, transcriptomic profiling showed upregulation of the recA gene, which is known to be important for DNA repair, implicating that cisplatin could interfere with DNA replication in P. aeruginosa. Cisplatin treatment significantly repressed the type III secretion system (T3SS), which is important for the secretion of exotoxins. Furthermore, cisplatin was also demonstrated to eradicate in vitro biofilms and in vivo biofilms in a murine keratitis model. This showed that cisplatin could be effectively used to eradicate biofilm infections which were otherwise difficult to be treated by conventional antibiotics. Although cisplatin is highly toxic for humans upon systemic exposure, a low toxicity was demonstrated with topical treatment. This indicated that higher-than-minimal inhibitory concentration (MIC) doses of cisplatin could be topically applied to treat persistent and recalcitrant P. aeruginosa infections.

Platinum Binds Proteins in the Endoplasmic Reticulum of S. cerevisiae and Induces Endoplasmic Reticulum Stress

Pt(II)-based anticancer drugs are widely used in the treatment of a variety of cancers, but their clinical efficacy is hindered by undesirable side effects and resistance. While much research has focused on Pt(II) drug interactions with DNA, there is increasing interest in proteins as alternative targets and contributors to cytotoxic and resistance mechanisms. Here, we describe a chemical proteomic method for isolation and identification of cellular protein targets of platinum compounds using Pt(II) reagents that have been modified for participation in the 1,3 dipolar cycloaddition "click" reaction. Using this method to visualize and enrich for targets, we identified 152 proteins in Pt(II)-treated Saccharomyces cerevisiae. Of interest was the identification of multiple proteins involved in the endoplasmic reticulum (ER) stress response, which has been proposed to be an important cytoplasmic mediator of apoptosis in response to cisplatin treatment. Consistent with possible direct targeting of this pathway, the ER stress response was confirmed to be induced in Pt(II)-treated yeast along with in vitro Pt(II)-inhibition of one of the identified proteins, protein disulfide isomerase.

Quantification of bindings of organometallic ruthenium complexes to GSTπ by mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) has been widely used to identify binding sites of metal complexes to proteins. However, the MS quantification of the metal-protein coordination remains a challenge. We have recently demonstrated by ESI-MS analysis that organometallic ruthenium complexes [(η(6)-arene)Ru(en)Cl](+) (arene=p-cymene (1), biphenyl (2) or 9,10-dihydrophenanthrene (3); en=ethylenediamine) bound to human glutathione-S-transferase π (GSTπ) at Cys15 and Cys48 within the G-site, and Cys102 and Met92 on the interface of the GSTπ dimer, showing inhibitory potency against the enzyme (J. Inorg. Biochem., 128 (2013) 77-84). Herein, we developed a mass spectrometric method to quantify the binding stoichiometry of the three complexes to GSTπ. The differences in signal intensities of the heavy-labelled peptides produced by tryptic digestion of the ruthenated GSTπ complexes and the respective light-labelled peptides in the tryptic digest of equimolar GSTπ were used to calculate the binding stoichiometry at specific residues. The results indicated that the pre-complexation of GSTπ with its substrate GSH significantly reduced the bindings of the ruthenium complexes at Met92 and Cys102, but had little impact on the bindings at Cys15 and Cys48. As the inhibitory activities of the ruthenium complexes against GSTπ are similar to those against GSTπ in complexation with GSH, these results suggest that the inhibition of the ruthenium complexes on GSTπ is attributed to the ruthenation at Cys15 and Cys48. The present work provides not only insights into the understanding on the inhibitory mechanism of ruthenium complexes GSTπ, but also a general method for quantitative characterization of metal-protein interactions.

Anticancer metallodrug research analytically painting the "omics" picture--current developments and future trends

Anticancer metallodrug development has for a long time been characterised by the similarity of new drug candidates to cisplatin and DNA as the primary target. Recent advances in bioanalytical techniques with high sensitivity and selectivity have revealed that metal-based drugs can undergo a wide range of biomolecular interactions beyond DNA and have generated interest in proteins as possible targets for metallodrugs. In fact, implementation of metallomics approaches that are able to reveal the fate of the compounds in biological systems can help to move drug development towards more targeted and rational design of novel metallodrugs. Additionally, proteomic screening and gene expression analysis can provide insight into physiological response to drug treatment and identify the reasons for drug resistance. Herein, we review selected applications which led to a better understanding of the mode of action of clinically established metal-based anticancer agents and novel metallodrug candidates.