Search Results (9)

PTD-FNK, a synthetic anti-apoptotic protein, has been shown to potently alleviate cellular injuries. However, the effects of PTD-FNK on oxidative defense in boar testicular Sertoli cells (SCs) against oxidative injury has not been explored. In this study, we show that exposure of SCs to 100 mg/L lipopolysaccharide (LPS) for 12 h leads to decreased survival rate, superoxide dismutase (SOD) activity, and increased malondialdehyde (MDA). Treatment with 0.01 nmol/L PTD-FNK for 4 h significantly enhanced the activity of SOD, catalase (CAT), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in SCs. Concurrently, PTD-FNK treatment effectively reduced the production of reactive oxygen species (ROS) and the levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG) in SCs. Moreover, using His pull-down and LC-MS techniques, we identified PTD-FNK-interacting proteins and confirmed that this protective effect may be mediated by the regulation of the Keap1-Nrf2 signaling pathway by PTD-FNK. Therefore, PTD-FNK alleviates LPS-induced oxidative stress via the Keap1/Nrf2 pathway, providing novel insights for the development of therapeutic agents targeting testicular oxidative damage. Full article

Prolonged periods of host-lethal infection by entomopathogenic fungi pose challenges to the development of biological control agents. The obligate entomopathogen C. obscurus, however, rapidly kills aphid hosts, warranting investigation. This study investigated the interaction between C. obscurus and a bean aphid Megoura crassicauda during the incubation period of infection, using transcriptome analysis to map host gene expression profiles. Results indicate C. obscurus-inoculated aphid activation of the wound healing immune responses, alongside suppression of the key molecules involved in Toll signaling, melanization, and metabolism. Furthermore, neuromotor system-related genes were upregulated, paralleling the intoxication observed in a nematode pest treated with C. obscurus-derived CytCo protein. To deepen interaction insights, a His-tag pull-down assay coupled with mass spectrometry analysis was conducted using CytCo as a bait to screen for potential aphid protein interactors. The proteins were identified based on the assembled transcriptome, and eleven transmembrane proteins were predicted to bind to CytCo. Notably, a protein of putatively calcium-transporting ATPase stood out with the highest confidence. This suggests that CytCo plays a vital role in C. obscurus killing aphid hosts, implicating calcium imbalance. In conclusion, C. obscurus effectively inhibits aphid immunity and exhibits neurotoxic potential, expediting the infection process. This finding facilitates our understanding of the complex host–pathogen interactions and opens new avenues for exploring biological pest management strategies in agroforestry. Full article

Puccinia striiformis f. sp. tritici is an obligate biotrophic fungus that causes destructive stripe rust disease in wheat. During infection, Pst secretes virulence effectors via a specific infection structure—the haustorium—inside host cells to disturb host immunity and promote fungal colonization and expansion. Hence, the identification and functional analyses of Pst effectors are of great significance in deciphering the Pst pathogenicity mechanism. Here, we identified one candidate Pst effector Pst_9302 that could suppress Bax-triggered cell death in Nicotiana benthamiana. qRT-PCR analyses showed that the transcript levels of Pst_9302 were highly increased during the early infection stages of Pst. The transient expression of Pst_9302 in wheat via the type-three secretion system (T3SS) significantly inhibited the callose deposition induced by Pseudomonas syringae EtHAn. During wheat–Pst interaction, Pst_9302 overexpression suppressed reactive oxygen species (ROS) accumulation and cell death caused by the avirulent Pst race CYR23. The host-induced gene silencing (HIGS) of Pst_9302 resulted in decreased Pst pathogenicity with reduced infection area. The results suggest that Pst_9302 plays a virulence role in suppressing plant immunity and promoting Pst pathogenicity. Moreover, wheat voltage-dependent anion channel 1 protein (TaVDAC1) was identified as candidate Pst_9302-interacting proteins by yeast two-hybrid (Y2H) screening. Pull-down assays using the His-Pst_9302 and GST-TaVDAC1 protein verified their interactions. These results suggest that Pst_9302 may modulate wheat TaVDAC1 to regulate plant immunity. Full article

The Protein Phosphatase type 1 catalytic subunit (PP1c) (PF3D7_1414400) operates in combination with various regulatory proteins to specifically direct and control its phosphatase activity. However, there is little information about this phosphatase and its regulators in the human malaria parasite, Plasmodium falciparum. To address this knowledge gap, we conducted a comprehensive investigation into the structural and functional characteristics of a conserved Plasmodium-specific regulator called Gametocyte EXported Protein 15, GEXP15 (PF3D7_1031600). Through in silico analysis, we identified three significant regions of interest in GEXP15: an N-terminal region housing a PP1-interacting RVxF motif, a conserved domain whose function is unknown, and a GYF-like domain that potentially facilitates specific protein–protein interactions. To further elucidate the role of GEXP15, we conducted in vitro interaction studies that demonstrated a direct interaction between GEXP15 and PP1 via the RVxF-binding motif. This interaction was found to enhance the phosphatase activity of PP1. Additionally, utilizing a transgenic GEXP15-tagged line and live microscopy, we observed high expression of GEXP15 in late asexual stages of the parasite, with localization predominantly in the nucleus. Immunoprecipitation assays followed by mass spectrometry analyses revealed the interaction of GEXP15 with ribosomal- and RNA-binding proteins. Furthermore, through pull-down analyses of recombinant functional domains of His-tagged GEXP15, we confirmed its binding to the ribosomal complex via the GYF domain. Collectively, our study sheds light on the PfGEXP15–PP1–ribosome interaction, which plays a crucial role in protein translation. These findings suggest that PfGEXP15 could serve as a potential target for the development of malaria drugs. Full article

Skin color variation and differentiation are bottlenecks in the aquaculture industry of red tilapia. The mitfa gene primarily regulates melanocyte survival and proliferation in fish skin pigmentation. In this study, a recombinant expression vector for Mitfa expression was successfully constructed. After induction and purification, nearly 600 μg of Mitfa protein was purified from the fermentation supernatant. His pull-down assay, followed by LC-MS/MS analysis, revealed 10 proteins that interact with the Mitfa protein. Five of these proteins were annotated in the melanogenesis and tyrosine metabolism pathways, including Krt, Tpm, Myh, Tyr and Dct. The purified Mitfa recombinant protein was injected into red tilapia, and its activity and function were examined. The expression levels of the mitfa, tyr, tyrp1, and dct genes increased greatly in the dorsal skin after injection (p < 0.05); meanwhile, the melanin content and tyrosinase activity increased significantly (p < 0.05). These findings provide a theoretical basis for comprehending the function and regulatory mechanism of the red tilapia mitfa gene. Full article

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi’s sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman’s disease. During KSHV lytic infection, lytic-related genes, categorized as immediate-early, early, and late genes, are expressed in a temporal manner. The transcription of late genes requires the virus-specific pre-initiation complex (vPIC), which consists of viral transcription factors. However, the protein-protein interactions of the vPIC factors have not been completely elucidated. KSHV ORF18 is one of the vPIC factors, and its interaction with other viral proteins has not been sufficiently revealed. In order to clarify these issues, we analyzed the interaction between ORF18 and another vPIC factor, ORF30, in living cells using the bimolecular fluorescence complementation (BiFC) assay. We identified four amino-acid residues (Leu29, Glu36, His41, and Trp170) of ORF18 that were responsible for its interaction with ORF30. Pull-down assays also showed that these four residues were required for the ORF18-ORF30 interaction. The artificial intelligence (AI) system AlphaFold2 predicted that the identified four residues are localized on the surface of ORF18 and are in proximity to each other. Thus, our AI-predicted model supports the importance of the four residues for binding ORF18 to ORF30. These results indicated that wet experiments in combination with AI may enhance the structural characterization of vPIC protein-protein interactions. Full article

Tilapia piscidin (TP) 4 is an antimicrobial peptide derived from Nile tilapia (Oreochromis niloticus), which shows broad-spectrum antibacterial activity and excellent cancer-killing ability in vitro and in vivo. Like many other antimicrobial peptides, TP4 treatment causes mitochondrial toxicity in cancer cells. However, the molecular mechanisms underlying TP4 targeting of mitochondria remain unclear. In this study, we used a pull-down assay on A549 cell lysates combined with LC-MS/MS to discover that TP4 targets adenine nucleotide translocator (ANT) 2, a protein essential for adenine nucleotide exchange across the inner membrane. We further showed that TP4 accumulates in mitochondria and colocalizes with ANT2. Moreover, molecular docking studies showed that the interaction requires Phe1, Ile2, His3, His4, Ser11, Lys14, His17, Arg21, Arg24 and Arg25 residues in TP4 and key residues within the cavity of ANT2. These findings suggest a mechanism by which TP4 may induce mitochondrial dysfunction to disrupt cellular energy metabolism. Full article

VirG is outer membrane protein of Shigella and affects the spread of Shigella. Recently it has been reported that apyrase influences the location of VirG, although the underlying mechanism remains poorly understood. The site of interaction between apyrase and VirG is the focus of our research. First we constructed recombinant plasmid pHIS-phoN2 and pS-(v_1–1102, v_53–758, v_759–1102, v_53–319, v_320–507, v_507–758) by denaturation-renaturation, the phoN2:kan mutant of Shigella flexneri 5a M90T by a modified version of the lambda red recombination protocol originally described by Datsenko and Wanner and the complemented strain M90TΔphoN2/pET24a(P_hisphoN2). Second, the recombinant plasmid pHIS-phoN2 and the pS-(v_1–1102, v_53–758, v_759–1102, v_53–319, v_320–507, v_507–758) were transformed into E. coli BL21 (DE3) and induced to express the fusion proteins. Third, the fusion proteins were purified and the interaction of VirG and apyrase was identified by pull-down. Fourth, VirG was divided and the interaction site of apyrase and VirG was determined. Finally, how apyrase affects the function of VirG was analyzed by immunofluorescence. Accordingly, the results provided the data supporting the fact that apyrase combines with the α-domain of VirG to influence the function of VirG. Full article

We designed a vector for the bacterial expression of recombinant antibodies fused to a double tag composed of 6xHis and the EPEA amino acid sequence. EPEA sequence (C tag) is tightly bound by a commercial antibody when expressed at the C-term end of a polypeptide. The antigen is released in the presence of 2 M MgCl₂. Consequently, constructs fused to the 6xHis-C tags can be purified by two successive and orthogonal affinity steps. Single-domain antibodies were produced either in the periplasmic or in the cytoplasmic space of E. coli. Surprisingly, the first affinity purification step performed using the EPEA-binding resin already yielded homogeneous proteins. The presence of the C tag did not interfere with the binding activity of the antibodies, as assessed by FACS and SPR analyses, and the C tag was extremely effective for immunoprecipitating HER2 receptor. Finally, the Alexa488-coupled anti-C tag allowed for simplification of FACS and IF analyses. These results show that a tag of minimal dimensions can be effectively used to improve the applicability of recombinant antibodies as reagents. In our hands, C tag was superior to His-tag in affinity purification and pull-down experiments, and practical in any other standard immune technique. Full article