Dual specificity phosphatases (DUSPs), a subfamily of the protein tyrosine phosphatase (PTP) family, dephosphorylate not only phosphotyrosine but also phosphoserine and phosphothreonine residues. Beyond the 26 members of this family in humans, DUSPs represent the only type of PTPs found across a wide range of microorganisms, including bacteria, archaea, and viruses. This review presents a comprehensive structural analysis of human and microbial DUSPs. These proteins commonly share core features, such as a typical DUSP fold, shallow active site pocket, signature active site motif known as the P-loop, and conserved aspartate residue that acts as a general acid/base. However, DUSPs from diverse microorganisms also display unique structural and functional characteristics. Pseudomonas aeruginosa TpbA is the only bacterial DUSP identified to date, while a second candidate was proposed in this review. Archaeal DUSPs are hyperthermostable, contain a unique motif in their P-loops, and employ dual general acid/base residues. Poxviral DUSPs are characterized by the formation of domain-swapped homodimers. The presence of DUSPs across all domains of life and viruses, along with their low specificity for phosphorylated amino acids and structural similarity to classical PTPs, suggests that DUSPs represent the ancestral form of PTPs.

A Gram-stain-negative, aerobic, non-motile, rod-shaped, and orange-pigmented bacterium, designated CJ426^T, was isolated from ginseng soil in Anseong, Korea. Strain CJ426^T grew optimally on Reasoner’s 2A agar at 30°C and pH 7.0 in the absence of NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain CJ426^T belonged to the family Chitinophagaceae and had the highest sequence similarity with Niabella hibiscisoli KACC 18857^T (98.7%). The 16S rRNA gene sequence similarities with other members of the genus Niabella ranged from 92.3% to 98.1%. Phylogenomic analyses and overall genomic relatedness indices, including average nucleotide identity, average amino acid identity, and the percentage of conserved proteins values, supported the classification of strain CJ426^T as a representative of a novel genus within the family Chitinophagaceae. Furthermore, genome-based analyses suggested that five members of the genus Niabella, including N. aquatica, N. defluvii, N. ginsengisoli, N. hibiscisoli, and, N. yanshanensis, should be separated from other Niabella species and be assigned as a novel genus. The major isoprenoid quinone of strain CJ426^T was menaquinone-7 (MK-7). The predominant polar lipids were phosphatidylethanolamine and six unidentified aminolipids. The major fatty acids were iso-C_15:0, iso-C_15:1 G, and iso-C_17:0 3-OH. The genome of strain CJ426^T was 6.3 Mbp in size, consisting of three contigs, with a G + C content of 41.9%. Based on a polyphasic taxonomic approach, strain CJ426^T represents a novel genus and species within the family Chitinophagaceae, for which the name Paraniabella aurantiaca gen. nov., sp. nov. is proposed. The type strain is CJ426^T (= KACC 23908^T = JCM 37728^T).

The Bacillus subtilis spore crust is an exceptionally robust proteinaceous layer that protects spores under extreme environmental conditions. Among its key components, CgeA, a glycosylation-associated protein, plays a critical role in modifying crust properties through its glycosylated moiety, enhancing spore dispersal in aqueous environments. In this study, we present the high-resolution cryo-electron microscopy structure of the core region of CgeA at 3.05 Å resolution, revealing a doughnut-like hexameric assembly. The N-terminal regions are disordered, whereas the C-terminal region forms the core of the hexamer. Although the loop containing Thr112 was not resolved in the density map, its location can be inferred from surrounding residues, suggesting that Thr112 is situated on the exposed surface of the hexamer. On the opposite face, a distinct electrostatic pattern is observed, featuring a negatively charged central pore and a positively charged outer surface. Modeling and biochemical studies with the putative glycosyltransferase CgeB provide insights into how the glycosyl group is transferred to Thr112. This study offers a molecular-level understanding of the assembly, glycosylation, and environmental adaptability of the B. subtilis spore crust, with valuable implications for controlling spore formation in industrial applications.

Yeast prion [PSI+], an amyloid form of the translation termination factor Sup35p/eRF3, causes translational stop codon readthrough by sequestering functional Sup35p. This unique phenotype may be analyzed via [PSI+]−suppressible nonsense alleles, and has greatly contributed to the advancement in yeast prion research. For comparing canonical reporters, like chromosomal ade1−14 or ade2−1, and plasmid-borne ura3−14, the de novo generation and characteristics of [PSI+] was investigated across common yeast laboratory strains (BY4741, 74D−694, and 779−6A). The results showed significant variability in [PSI+] induction frequency among strains. [PSI+] was successfully induced in BY4741 and frequently in 74D−694 (via Ade⁺ selection), but not in 779−6A. Notably, [PSI+] clones, even from identical genetic backgrounds, displayed vastly different nonsense suppression phenotypes depending on the reporter allele used; resulting in diverse growth patterns and suppression levels. Quantitative analyses revealed that prion seed counts fluctuated significantly based on the detection allele and observed phenotype. Furthermore, Sup35p aggregate visualization revealed distinct structural patterns between BY4741 and 74D−694, indicating strain-specific differences. Transferring [PIN+] prion variants from different strains into a common [psi−][pin−] background yielded similar [PSI+] inducibility and seed numbers, suggesting that the observed phenotypic and quantitative diversities of [PSI+] prions stem primarily from the interplay between the specific reporter detection system and the host strain's genetic background rather than solely from inherent differences in the initial [PIN+] prion or fundamental changes in the [PSI+] protein itself. This study underscores the crucial need to consider both the detection methodology and host genetic context for accurate prion variant characterization.

Streptococcus mutans is a Gram-positive pathogen that causes dental caries and subsequent pulpal infection leading to pulpitis. Although dendritic cells (DCs) are known to be involved in disease progression and immune responses during S. mutans infection, little is known about which component of S. mutans is responsible for the DC responses. Although the mannose phosphotransferase system (Man-PTS) is the primary sugar transporter of S. mutans, it is also a potential virulence factor. Since Man-PTS subunit IID (ManIID) embedded on the bacterial membrane is indispensable for Man-PTS function, we investigated its role in the maturation and activation of DCs stimulated with a ManIID-deficient strain (Δpts) of S. mutans and recombinant ManIID (rManIID) protein. When mouse bone marrow-derived DCs were treated with heat-killed S. mutans wild-type (WT) or Δpts, bacterial adherence and internalization of Δpts were lower than those of WT. Moreover, the heat-killed S. mutans Δpts strain was inferior to the wild-type in inducing expression of phenotypic maturation markers, such as CD80, CD86, MHC-I, and MHC-II, and proinflammatory cytokine, IL-6. In line with the trends in marker expression, the endocytic capacity of DCs treated with the Δpts strain was comparable to that of untreated DCs whereas DCs treated with the WT strain dose-dependently lost their endocytic capacity. Furthermore, rManIID dose-dependently promoted both phenotypic maturation marker expression and IL-6 production by DCs. Collectively, these results demonstrate that ManIID plays a crucial role in the adhesion and internalization of S. mutans into DCs and is one of the major immune-stimulating agents responsible for maturation and activation of DCs during S. mutans infection.

Nosocomial infections caused by Pseudomonas aeruginosa (P. aeruginosa) have become increasingly common, particularly among immunocompromised individuals, who experience high mortality rates and prolonged treatment durations due to the limited availability of effective therapies. In this study, we screened for anti-ExoS compounds targeting P. aeruginosa and identified pycnogenol (PYC) as a potent inhibitor of the type III secretion system (T3SS), a major virulence mechanism responsible for the translocation of effectors such as ExoS. Using ELISA, western blotting, and real-time PCR analyses in both P. aeruginosa and infected H292 cells, we found that PYC significantly reduced T3SS activity. Mechanistically, PYC suppressed the transcription of T3SS-related genes by downregulating exsA expression in P. aeruginosa. Furthermore, pretreatment with PYC attenuated the cytotoxic effects and reduced the expression of proinflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-18 (IL-18), in P. aeruginosa-infected H292 cells. These effects were associated with the inhibition of NF-κB signaling and inflammasome activation. Taken together, our findings suggest that PYC may serve as a promising therapeutic candidate against P. aeruginosa infections by targeting T3SS-mediated virulence and modulating host inflammatory responses.

Atopic dermatitis (AD) is a widespread inflammatory skin condition that affects the population worldwide. Given the implication of microbiota in AD pathogenesis, we investigated whether human-derived Lactobacillus strains could modulate AD. In this study, we identified Lactobacillus crispatus KBL693 as a probiotic candidate for AD treatment. In vitro, KBL693 suppressed mast cell degranulation and IL-4 production by T cells, suggesting its ability to attenuate key type 2 immune responses. Consistent outcomes were observed in a murine AD model, where oral administration of KBL693 alleviated disease symptoms and reduced hallmark type 2 immune markers, including plasma IgE as well as IL-4, IL-5, and IL-13 levels in skin lesions. In addition to downregulating these AD-associated immune responses, KBL693 promoted regulatory T cell (Treg) expansion in mesenteric lymph nodes, indicating its potential to restore immune balance. Collectively, these findings highlight the therapeutic potential of KBL693 for AD through enhancement of Tregs and suppression of type 2 immune responses.