Biology subjects

Kitao, T.

Publications and source records attributed to Kitao, T..

4 recordsLinked to original sources

bioRxiv2023

Multi-tiered actions of Legionella effectors to modulate host Rab10 dynamics

Rab GTPases are representative targets of manipulation by intracellular bacterial pathogens for hijacking membrane trafficking. Legionella pneumophila recruits many Rab GTPases to its vacuole and exploits their activities. Here, we found that infection-associated regulation of Rab10 dynamics involves ubiquitin signaling cascades mediated by the SidE and SidC families of Legionella ubiquitin ligases. Phosphoribosyl-ubiquitination of Rab10 catalyzed by the SidE ligases is crucial for its recruitment to the bacterial vacuole. SdcB, the previously uncharacterized SidC family effector, resides on the vacuole and contributes to retention of Rab10 at the late stages of infection. We further identified MavC as a negative regulator of SdcB. By the transglutaminase activity, MavC crosslinks ubiquitin to SdcB and suppresses its function, resulting in elimination of Rab10 from the vacuole. These results demonstrate that the orchestrated actions of many L. pneumophila effectors fine-tune the dynamics of Rab10 during infection.

microbiology↗

bioRxiv2022

Mechanism of Lys6 poly-ubiquitin specificity by the L. pneumophila deubiquitinase LotA

The versatility of ubiquitination to impose control over vast domains of eukaryotic biology is due, in part, to diversification through differently-linked poly-ubiquitin chains. Deciphering the signaling roles for some poly-ubiquitin chain types, including those linked via K6, has been stymied by a lack of stringent linkage specificity among the implicated regulatory proteins. Forged through strong evolutionary pressures, pathogenic bacteria have evolved intricate mechanisms to regulate host ubiquitin, and in some cases even with exquisite specificity for distinct poly-ubiquitin signals. Herein, we identify and characterize a deubiquitinase domain of the secreted effector protein LotA from Legionella pneumophila that specifically regulates K6-linked poly-ubiquitin during infection. We demonstrate the utility of LotA as a tool for studying K6 poly-ubiquitin. By determining apo and diUb-bound structures, we identify the mechanism of LotA activation and K6 poly-ubiquitin specificity, and identify a novel ubiquitin-binding domain utilized among bacterial deubiquitinases.

biochemistry↗

bioRxiv2022

Tackling Recalcitrant Pseudomonas aeruginosa Infections In Critical Illness via Anti-virulence Monotherapy

Intestinal barrier derangement allows intestinal bacteria and their products to translocate to the systemic circulation. Pseudomonas aeruginosa (PA) superimposed infection in critically ill patients increases gut permeability and leads to gut-driven sepsis. PA infections are challenging due to multi-drug resistance (MDR), biofilms, and/or antibiotic tolerance. Inhibition of the quorum-sensing transcriptional regulator MvfR(PqsR) is a desirable anti-PA strategy as MvfR controls multiple acute and chronic virulence functions. Here we show that MvfR promotes intestinal permeability and report novel potent anti-MvfR compounds, the N-Aryl Malonamides (NAMs) resulting from extensive structure-activity-relationship studies and thorough assessment of the inhibition of MvfR-controlled virulence functions. This novel class of anti-virulence non-native ligand-based agents has a half-maximal inhibitory concentration in the nanomolar range and strong target engagement. Using a NAM lead in monotherapy protects murine intestinal barrier function, abolishes MvfR-regulated small molecules, ameliorates bacterial dissemination, and lowers inflammatory cytokines. This study demonstrates the importance of MvfR in PA-driven intestinal permeability. It underscores the utility of anti-MvfR agents in maintaining gut mucosal integrity, which should be part of any successful strategy to prevent/treat PA infections and associated gut-derived sepsis in critical illness settings. NAMs provide for the development of crucial preventive/therapeutic monotherapy options against untreatable MDR PA infections.

microbiology↗

bioRxiv2020

Isolation and characterization of a novel phage SaGU1 that infects Staphylococcus aureus clinical isolates from patients with atopic dermatitis

The bacterium Staphylococcus aureus, which grows on healthy human skin, may cause diseases such as atopic dermatitis (AD). Treatment for such AD cases involves antibiotic use; however, alternate treatments are preferred owing to the development of antimicrobial resistance. This study aimed to characterize the novel bacteriophage SaGU1 as a potential agent for phage therapy to treat S. aureus infections. SaGU1 that infects S. aureus strains previously isolated from the skin of patients with AD was screened from sewage samples in Gifu, Japan. Its genome was sequenced and analyzed using bioinformatics tools, and the morphology, lytic activity, stability, and host range of the phage were determined. The SaGU1 genome consisted of 140,909 bp with an average GC content of 30.2%. The viral chromosome contained putative 225 protein-coding genes and four tRNA genes, carrying neither toxic nor antibiotic resistance genes. Electron microscopy analysis revealed that SaGU1 belongs to the Myoviridae family. Stability tests showed that SaGU1 was heat-stable under physiological and acidic conditions. Host-range testing revealed that SaGU1 could infect a broad range of S. aureus clinical isolates present on the skin of patients with AD, whereas it did not kill strains of Staphylococcus epidermidis, which are symbiotic bacteria in the human skin microbiota. Our data suggest that SaGU1 is a potential candidate for developing a phage therapy to treat AD caused by pathogenic S. aureus.

microbiology↗