A novel Xanthomonas citri subsp. citri NADPH quinone reductase involved in salt stress response and virulence

The Candida albicans ζ-crystallin homolog Zta1 promotes resistance to oxidative stress

IMPORTANCE

Candida albicans is an important human pathogen that can cause lethal systemic infections. The ability of C. albicans to colonize and establish infections is closely tied to its highly adaptable nature and capacity to resist various types of stress, including oxidative stress. Previous studies showed that four C. albicans proteins belonging to the flavodoxin-like protein family of quinone reductases are needed for resistance to quinones and virulence. Therefore, in this study, we examined the role of a distinct type of quinone reductase, Zta1, and found that it acts in conjunction with the flavodoxin-like proteins to protect against oxidative stress.

The Candida albicans ζ-crystallin homolog Zta1 promotes resistance to oxidative stress

The fungal pathogen Candida albicans is capable of causing lethal infections in humans. Its pathogenic potential is due in part to the ability to resist various stress conditions in the host, including oxidative stress. Recent studies showed that a family of four flavodoxin-like proteins (Pst1, Pst2, Pst3, Ycp4) that function as quinone reductases promotes resistance to oxidation and is needed for virulence. Therefore, in this study Zta1 was examined because it belongs to a structurally distinct family of quinone reductases that are highly conserved in eukaryotes and have been called the ζ-crystallins. The levels of Zta1 in C. albicans rapidly increased after exposure to oxidants, consistent with a role in resisting oxidative stress. Accumulation of reactive oxygen species was significantly higher in cells lacking ZTA1 upon exposure to quinones and other oxidants. Furthermore, deletion of ZTA1 in a mutant lacking the four flavodoxin-like proteins, resulted in further increased susceptibility to quinones, indicating that these distinct quinone reductases work in combination. These results demonstrate that Zta1 contributes to C. albicans survival after exposure to oxidative conditions, which increases the understanding of how C. albicans resists stressful conditions in the host.

Enhancing intracellular NADPH bioavailability through improving pentose phosphate pathway flux and its application in biocatalysis asymmetric reduction reaction

The intracellular NAD(P)H insufficiency is the key factor which limits the reduced product (such as chiral alcohols) synthesis by whole cell biocatalysis or microbial cell factory. In this paper, we reported a novel solution to increase NADPH supply through strengthening the pentose phosphate pathway (PPP) flux with overexpression of extra zwf (gene for glucose 6-phosphatedehydrogenase) and glk (gene for glucokinase) by recombinant Escherichia coli BL21(DE3)/pETDuet-1-glk-zwf and pET28a-bccr containing a carbonyl reductase gene bccr. The amount of intracellular NADPH was significantly increased from 150.3 μmol/L to 681.8 μmol/L after strengthening the PPP flux, which was 4.5-fold to that of the control. It was applied to improve the asymmetric reduction of 4-chloroacetoacetate to ethyl S-4-chloro-3-hydroxybutylate catalyzed by the BcCR, which increased the reaction yield 2.8-fold to the control. This strategy provides a new way to increase NADPH supply in E. coli cell factories.

Every cloud has a silver lining: how abiotic stresses affect gene expression in plant-pathogen interactions

Current environmental and climate changes are having a pronounced influence on the outcome of plant-pathogen interactions, further highlighting the fact that abiotic stresses strongly affect biotic interactions at various levels. For instance, physiological parameters such as plant architecture and tissue organization together with primary and specialized metabolism are affected by environmental constraints, and these combine to make an individual plant either a more or less suitable host for a given pathogen. In addition, abiotic stresses can affect the timely expression of plant defense and pathogen virulence. Indeed, several studies have shown that variations in temperature, and in water and mineral nutrient availability affect the expression of plant defense genes. The expression of virulence genes, known to be crucial for disease outbreak, is also affected by environmental conditions, potentially modifying existing pathosystems and paving the way for emerging pathogens. In this review, we summarize our current knowledge on the impact of abiotic stress on biotic interactions at the transcriptional level in both the plant and the pathogen side of the interaction. We also perform a metadata analysis of four different combinations of abiotic and biotic stresses, which identifies 197 common modulated genes with strong enrichment in Gene Ontology terms related to defense . We also describe the multistress-specific responses of selected defense-related genes.