viciae 3841

Cuproptosis: unveiling a new frontier in cancer biology and therapeutics

Copper plays vital roles in numerous cellular processes and its imbalance can lead to oxidative stress and dysfunction. Recent research has unveiled a unique form of copper-induced cell death, termed cuproptosis, which differs from known cell death mechanisms. This process involves the interaction of copper with lipoylated tricarboxylic acid cycle enzymes, causing protein aggregation and cell death. Recently, a growing number of studies have explored the link between cuproptosis and cancer development. This review comprehensively examines the systemic and cellular metabolism of copper, including tumor-related signaling pathways influenced by copper. It delves into the discovery and mechanisms of cuproptosis and its connection to various cancers. Additionally, the review suggests potential cancer treatments using copper ionophores that induce cuproptosis, in combination with small molecule drugs, for precision therapy in specific cancer types.

Proteomic and Mutant Analysis of Hydrogenase Maturation Protein Gene hypE in Symbiotic Nitrogen Fixation of Mesorhizobium huakuii

Hydrogenases catalyze the simple yet important redox reaction between protons and electrons and H2, thus mediating symbiotic interactions. The contribution of hydrogenase to this symbiosis and anti-oxidative damage was investigated using the M. huakuii hypE (encoding hydrogenase maturation protein) mutant. The hypE mutant grew a little faster than its parental 7653R and displayed decreased antioxidative capacity under H2O2-induced oxidative damage. Real-time quantitative PCR showed that hypE gene expression is significantly up-regulated in all the detected stages of nodule development. Although the hypE mutant can form nodules, the symbiotic ability was severely impaired, which led to an abnormal nodulation phenotype coupled to a 47% reduction in nitrogen fixation capacity. This phenotype was linked to the formation of smaller abnormal nodules containing disintegrating and prematurely senescent bacteroids. Proteomics analysis allowed a total of ninety differentially expressed proteins (fold change > 1.5 or <0.67, p < 0.05) to be identified. Of these proteins, 21 are related to stress response and virulence, 21 are involved in transporter activity, and 18 are involved in energy and nitrogen metabolism. Overall, the HypE protein is essential for symbiotic nitrogen fixation, playing independent roles in supplying energy and electrons, in bacterial detoxification, and in the control of bacteroid differentiation and senescence.

H2 O2 , NO, and H2 S networks during root development and signalling under physiological and challenging environments: Beneficial or toxic?

Hydrogen peroxide (H₂ O₂ ) is a reactive oxygen species (ROS) and a key modulator of the development and architecture of the root system under physiological and adverse environmental conditions. Nitric oxide (NO) and hydrogen sulphide (H₂ S) also exert myriad functions on plant development and signalling. Accumulating pieces of evidence show that depending upon the dose and mode of applications, NO and H₂ S can have synergistic or antagonistic actions in mediating H₂ O₂ signalling during root development. Thus, H₂ O₂ -NO-H₂ S crosstalk might essentially impart tolerance to elude oxidative stress in roots. Growth and proliferation of root apex involve crucial orchestration of NO and H₂ S-mediated ROS signalling which also comprise other components including mitogen-activated protein kinase, cyclins, cyclin-dependent kinases, respiratory burst oxidase homolog (RBOH), and Ca²⁺ flux. This assessment provides a comprehensive update on the cooperative roles of NO and H₂ S in modulating H₂ O₂ homoeostasis during root development, abiotic stress tolerance, and root-microbe interaction. Furthermore, it also analyses the scopes of some fascinating future investigations associated with strigolactone and karrikins concerning H₂ O₂ -NO-H₂ S crosstalk in plant roots.

Effect of the Monothiol Glutaredoxin GrxD on 2,4-Diacetylphloroglucinol Biosynthesis and Biocontrol Activity of Pseudomonas fluorescens 2P24

Pseudomonas fluorescens 2P24 is a plant root-associated bacterium that suppresses several soilborne plant diseases due to its production of the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG). The biosynthesis of 2,4-DAPG is controlled by many regulatory elements, including the global regulator of the Gac/Rsm regulon and the pathway-specific repressor PhlF. In this work, a novel genetic element grxD, which encodes the monothiol glutaredoxin GrxD, was identified and characterized in the production of 2,4-DAPG in P. fluorescens 2P24. Our data showed that the mutation of grxD remarkably decreased 2,4-DAPG production. GrxD lost its ability to alter the production of 2,4-DAPG when the active-site CGFS motif of GrxD was mutated by site-directed mutagenesis. Further studies showed that the RsmA and RsmE proteins were essential for the GrxD-mediated regulation of 2,4-DAPG and exoprotease production. In addition, our data revealed that the deletion of grxD increased the expression of phlF, which negatively regulated the production of 2,4-DAPG. In addition, the grxD mutant was severely impaired in the biocontrol effect against the bacterial wilt of tomato. Overall, our results indicated that the monothiol glutaredoxin GrxD is involved in the production of 2,4-DAPG of P. fluorescens by influencing the Gac/Rsm global signaling pathway and transcriptional regulator PhlF and is essential for the biocontrol properties.

The Mesorhizobium huakuii transcriptional regulator AbiEi plays a critical role in nodulation and is important for bacterial stress response

Background

Bacterial abortive infection (Abi) systems are type IV toxin–antitoxin (TA) system, which could elicit programmed cell death and constitute a native survival strategy of pathogenic bacteria under various stress conditions. However, no rhizobial AbiE family TA system has been reported so far. Here, a M. huakuii AbiE TA system was identified and characterized.

Results

A mutation in M. huakuii abiEi gene, encoding an adjacent GntR-type transcriptional regulator, was generated by homologous recombination. The abiEi mutant strain grew less well in rich TY medium, and displayed increased antioxidative capacity and enhanced gentamicin resistance, indicating the abiEi operon was negatively regulated by the antitoxin AbiEi in response to the oxidative stress and a particular antibiotic. The mRNA expression of abiEi gene was significantly up-regulated during Astragalus sinicus nodule development. The abiEi mutant was severely impaired in its competitive ability in rhizosphere colonization, and was defective in nodulation with 97% reduction in nitrogen-fixing capacity. The mutant infected nodule cells contained vacuolation and a small number of abnormal bacteroids with senescence character. RNA-seq experiment revealed it had 5 up-regulated and 111 down-regulated genes relative to wild type. Of these down-regulated genes, 21 are related to symbiosis nitrogen fixation and nitrogen mechanism, 16 are involved in the electron transport chain and antioxidant responses, and 12 belong to type VI secretion system (T6SS).

Conclusions

M. huakuii AbiEi behaves as a key transcriptional regulator mediating root nodule symbiosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02304-0.