查看更多>>摘要：The bifunctional alcohol/aldehyde dehydrogenase (AdhE), one of the key enzymes in the bacterial ethanol anaerobic fermentation pathway, is critical for appropriate expression of the genes for the utilization of carbon sources. Knowledge about its global roles in modulating gene expression and metabolomics remains limited. Edwardsiella bacteria includes several important zoonotic pathogenic species including Edwardsiella piscicida, a leading fish pathogen that causes severe economic losses in the aquaculture industry. It is well known to utilize few sugars. In this study, we showed that AdhE is involved in various processes including sugar utilization, bacteria growth, intracellular pH homeostasis, type III/VI secretion system (T3/T6SS) production, and survival in fish. Moreover, our unbiased metabolomics approaches revealed that AdhE modulates a large quantity of metabolic pathways, including amino acids, tricarboxylic acid (TCA) intermediates, sugar and fatty acids. Pull down and Co-immunoprecipitation (IP) analysis revealed that AdhE interacts with the phospho-transferase system component PtsH that supports the transform of its PTS sugars including mannose to mannose-6P, the established metabolic ligand modulating EvrA activity to control T3/T6SS expression. Collectively, AdhE appears to play important roles in bacterial adapting to the internal environment changes by regulating sugar metabolic pathways and bacterial virulence expression. These observations support a model in which AdhE acts a macromolecule hub accommodating proteins to modulate the PTS and other signaling cascades related to pathogenesis and environmental adaptation in bacterial pathogens, which may provide new perspectives for attempts to attenuate bacterial virulence.
查看更多>>摘要：Fusarium oxysporum f. sp. lycopersici (Fol) is majorly responsible for causing vascular wilt disease in tomato by blocking transpirational pull, thereby interfering and suppressing overall host immune response. This is mainly achieved by fungal invasion and colonization within the host, resulting in hyphal formation that instigates secondary infection response inside the plant. Earlier reports show the role of fasciclin-like proteins (FLPs) in cell-to-cell adhesions and signaling cascade. Moreover, deletion mutant of FLPs explained its role in development stages of Magnaporthe oryzae and Lentula edodes. Therefore, in present study, based on bioinformatic analysis, we have identified putative FoFLP genes encoding Fusarium-specific fasciclin like proteins. We have exploited the RNAi technology to analyse and understand role of these FoFLPs in virulence during wilt disease in tomato. Interestingly, the morphogenesis of fungal RNAi transformants of FoFLP1, FoFLP3, FoFLP4 and FoFLP5 showed significant reduction in spore count and spore germination frequency, thereby suggesting role of FoFLPs in conidiation. Furthermore, we have detected FoFLP1, FoFLP3, FoFLP4 and FoFLP5 specific siRNAs in the respective fungal transformants, using stem-loop RT-PCR and northern hybridization suggesting targeting of cognate FoFLPs transcripts. Moreover, the fruit invasion and plant infection assays using FoFLP fungal transformants showed late onset of disease with significant reduction in disease symptoms in the infected plants. Although the FoFLP-RNAi fungal transformants entered the host plant by penetrating root cortex, the infected plants showed minimum fungal colonization as a result of siRNA-mediated targeting of endogenously expressed FoFLPs. This further inhibited the propagation of fungal RNAi transformants within root cortex and affected its ability to cause secondary infection response, which led to reduced disease incidence and disease severity index. Altogether, our results show that FoFLPs might play an important role in conidiation and pathogenicity, and can serve as potent RNAi targets. Therefore, Host-Induced Gene Silencing (HIGS) can effectively be used to target FoFLPs in order to raise tomato transgenics resistant to Fusarium wilt.
Bhat, Raja Aadil HussainKhangembam, Victoria C.Thakuria, DimpalPant, Vinita...
14页
查看更多>>摘要：Antimicrobial peptides (AMPs) are considered alternatives to classical antibiotics and may become an excellent candidate for tackling antimicrobial resistance in aquaculture. Designing novel antimicrobial peptides for curbing antimicrobial resistance in aquaculture is paramount in one health approach. In this study, a short and compositionally simple peptide, KK16, was designed. KK16 is amphipathic with a net charge of + 6. Molecular docking results revealed that KK16 has a strong affinity towards two virulence proteins of Aeromonas sobria; aerolysin and outer membrane protein (omp). The peptide was synthesised using Fmoc-chemistry, and its antimicrobial efficacy was evaluated in vitro against A.sobria, A. salmonicida, Edwardsiella tarda, A. hydrophila, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis and methicillinresistant S. aureus. The KK16 AMP showed potent activity against the tested bacterial pathogens as revealed by the MIC and MBC, ranging from 7.81 to 500 mu M, and 15-900 mu M, respectively. Moreover, the peptide was stable at higher temperatures and retained its activity in presence of serum and salt. The peptide displayed less haemolytic and cytotoxic activity even at higher concentrations. In peptide-DNA binding assay, KK16 showed its binding potential with bacterial genomic DNA and thus, may interfere with replication. Fluorescent microscopy revealed the uptake of propidium iodide by peptide treated bacterial cells, indicating its membrane disruption activity. In in vivo experiment, KK16 peptide completely inhibited the growth of Saprolegnia parasitica fungus at >= 30 mu M peptide concentrations in embryonated fish eggs. The results indicate that KK16 peptide is stable, possess potent antibacterial and antifungal activity, less cytotoxic to host cells, and hence may prove to be a promising anti-infective agent for combating common bacterial and fungal infections.
查看更多>>摘要：In recent years, Candida glabrata has emerged as a clinically important pathogen causing invasive infections and death. This review highlights the main virulence factors of this fungus and its strategies to subvert the cell response after invasion. Additionally, we emphasize the intracellular behavior and relationship of C. glabrata with several cells. We contrast these features with some fascinating strategies exhibited by M. tuberculosis to highlight that C. glabrata is a successful pathogen and an artist manipulating the immune response like M. tuberculosis.
查看更多>>摘要：Protein kinases uniquely expressed in Plasmodium represent attractive drug targets. Previous studies have reported that Plasmodium falciparum Protein kinase 9 (Pk9) phosphorylates regulatory serine 106 of the ubiquitinconjugating enzyme (Ubc13) thereby negatively regulating its activity. We investigated the effect of Pk9 depletion and Ubc13 mutation at S106 on the progression of rodent malaria model P. berghei life cycle. Our studies demonstrate that while phosphorylation of the regulatory serine 106 of Ubc13 is essential in blood stages, the lack of Pk9 expression neither altered Ubc13 phosphorylation nor parasite viability at all life cycle stages, though Ubc13 and Pk9 showed co-localization in the cytosol of erythrocytic and liver stages. Further, phosphorylation of Ubc13 in the absence of Pk9 reiterated the redundancy of its regulation in P. berghei. These results highlight the indispensable role of Ubc13 in P. berghei life cycle and redundancy in its phosphorylation by protein kinase and reiterate the need to validate novel gene function through genetic approaches for drug development strategies.
Goulin, Eduardo Henriquede Lima, Thiago Antoniodos Santos, Paulo Jose CamargoMachado, Marcos Antonio...
10页
查看更多>>摘要：The citrus crop is one of the most important culture worldwide, being Brazil the world highest producer of sweet oranges. The challenge for this culture is the constant attack by several pathogens that cause economically losses. Among the fungal diseases the post-bloom fruit drop causes dramatically losses in production, characterized by damages in the blossoms that causes fruit infeasibility and early drop, one of the causal agent is Colletotrichum abscissum. The pathogen control is based in chemical applications, irrespective of crops and fungicides used, development of fungicide-resistant pathogen populations is a problem in agriculture. New technologies are being applied every year to better understand the pathogens biology, which can contribute to plant diseases control as an alternative to chemical compounds. The RNA interference emerged as a potential technology for gene function studies as well as an approach for pathogens control. The fungicides compounds have action in different targets, such as the succinate dehydrogenase (SDH), which plays a hole in cell respiration. Therefore, here we investigate the functionality of the RNAi machinery of C. abscissum and test genetically whether the chemically pre-defined fungal SDH target may represent a promising target gene in RNAi based control strategies. The C. abscissum RNAi machinery was functionally proven by silencing of gene report. Then, the silencing of SDH subunits were induced and verified. In addition, the C. abscissum mutants generated for this study made possible the fungus infection process investigation. Furthermore, knockdown mutants of succinate dehydrogenase subunits genes resulted in morphological and significant pathogenicity changes. Thus, in conclusion, we suggest that the RNA interference is an important tool that can be exploited to post bloom fruit drop disease control and also the chemical fungicide target are still useful in the new technologies control strategies.
查看更多>>摘要：Sunlight is pivotal for our survival, and daily UV exposure has impacted the evolutionary course of all forms of life, from microorganisms to humans. Deciphering the role of UVR in regulating the microbial dynamics of environmental and host-associated microbes is crucial. UVR may be responsible for affecting skin pathology by influencing the skin microbiome, both qualitatively and quantitatively, as evident in low-dose narrow-band UVB phototherapy. Some findings have suggested that the skin microbiome has immunomodulatory roles when exposed to UVR; however, its involvement in UV screening or protection has yet to be fully explored. Furthermore, numerous skin disorders are associated not only with an altered skin microbiome but also with an altered gut microbiome. Hence, the skin-gut axis needs to be in physiological homeostasis and immunological harmony. The purpose of this review is to examine the impact of natural UVR on human immunomodulatory mechanisms and the associated cutaneous microbiome, with an emphasis on interactions among UVR, skin homeostasis, vitamin D, and the related skin-gut axis. With the 'nature as an inspiration' approach, ongoing research is trying to decipher photoprotective secrets in several microbial-based natural compounds to be used as sunscreens or other topical formulations. In addition, various probiotics have also been shown to have significant antioxidant, antiwrinkle, and antiaging effects that ameliorate UV-induced cellular and molecular damage, as highlighted in the review. These cosmetics, nutricosmetics, and probiotaceuticals will undoubtedly be next-generation solutions against photoaging and maintaining skin health.
查看更多>>摘要：Staphylococcus aureus (Sau) plays an important role in human infections occurring in both the community and hospital settings. Sau-related chronic and relapsing infections are mainly attributed to small-colony variants (SCVs), a type of subpopulation that has a size one-tenth that of normal colonies and is accompanied by several unique characteristics, including a lack of or reduced pigmentation, decreased hemolytic activity, increased biofilm formation, enhanced resistance to antimicrobials, upregulated genes encoding adhesion molecules, and downregulated genes for virulence factors. This review summarizes the significance of genetic mutations involved in diverse biosynthesis pathways that contribute to Sau-SCV promotion. Sau-SCV-caused persistent infections and the prospects and challenges faced in the treatment of Sau-SCV infections are addressed. Progress in the management of Sau-SCVs may provide guidance for addressing the long-term and recurrent infections caused by other bacterial SCVs.
Mitra, MohorSingh, RashikaGhissing, UpashanaDas, Amit K....
13页
查看更多>>摘要：Alcohol acetyltransferases (AATs) are a group of enzymes that catalyze the formation of esters from different alcohols and acetyl-CoA. However, these enzymes are not well characterized with regard to synthesis of anti fungal compounds. The present study aims to investigate the AAT enzyme from Geotrichum candidum PF005, an endophytic yeast-like fungus that emits fruity scented antifungal volatiles, primarily comprising of acetate esters. After PCR-based cloning of the GcAAT gene, the encoded enzyme was characterized structurally through in silico methods and functionally via heterologous expression in Saccharomyces cerevisiae. In native host, the single copy GcAAT gene exhibited induced expression upon supplementation with metabolic precursors, like L-leucine (Leu) or alpha-ketoisocaproate (alpha-KIC). Docking studies using the modelled structure of GcAAT revealed differential but favourable binding interactions for three alcohol substrates (i.e., isoamyl alcohol, isobutyl alcohol and 2-phenyl ethanol) and the co-substrate acetyl-CoA. Binding sites for both substrate and co-substrate are found to be located inside a tunnel identified in the structure, wherein the H208 of the acetyltransferase conserved motif HXXXD was found at a hydrogen bond distance from the substrate. Functional complementation of GcAAT in S. cerevisiae AAT knockout strain caused 32% decrease in dry biomass weight of the test phytopathogenic fungus, Rhizoctonia solani as compared to the control (AAT knockout strain with empty plasmid) after 72 h of incubation due to the emitted volatiles. When the transformed yeast cells were fed with Leu and alpha-KIC, the relative abundance of the isoamyl acetate ester increased by 21% and 48%, respectively as compared to the control (without precursor). Further analysis documented that volatiles from alpha-KIC fed GcAAT transformant exhibited 58% higher antifungal activity against the test fungus R. solani than the control, engendered by increased oxidative stress that led to distorted mycelial morphology and increased hyphal branching. Together, the augmented antifungal effect displayed by the GcAAT expressing S. cerevisiae AAT knockout strain is clearly attributable to the acetate esters, especially isoamyl acetate, which are inherently produced in endophytic G. candidum PF005 as antifungal volatiles.
查看更多>>摘要：Aureobasidium melanogenum HN6.2 is a high siderophore-producing yeast-like fungal strain. After blocking siderophore biosynthesis and attenuating the expression of the ornithine carbamoyltransferase gene (the OTC gene), the obtained D-LCFAO-cre strain produced 2.1 +/- 0.02 mg of intracellular L-ornithine per mg of the protein. The overexpression of the L-ornithine decarboxylase gene (the SPE1-S gene) from Saccharomyces cerevisiae in the mutant D-LCFAO-cre could make the transformant E-SPE1-S synthesize 3.6 +/- 0.1 of intracellular ornithine per mg of protein and produce 10.5 g/L of putrescine. The further overexpression of the ArgB/C gene encoding bifunctional acetylglutamate kinase/N-acetyl-gamma-glutamyl-phosphate reductase in the transformant E-SPE1-S caused the transformant E-SPE1-S-ArgB/C to accumulate L-ornithine (4.2 mg/mg protein) and to produce 21.3 g/L of putrescine. During fed-batch fermentation, the transformant E-SPE1-S-ArgB/C could produce 33.4 g/L of putrescine, the yield was 0.96 g/g of glucose, and the productivity was 0.28 g/L/h. The putrescine titer was much higher than that produced by most engineered strains obtained thus far.
NSTL
Elsevier