Biology subjects

Ouyang, R.

Publications and source records attributed to Ouyang, R..

4 recordsLinked to original sources

bioRxiv2025

Using cryogenic electron microscopy methods to gain insight into structure and initial host attachment of the flagellotropic bacteriophage 7-7-1

Understanding the structural and functional mechanisms of bacteriophage 7-7-1, the flagellotropic phage infecting Agrobacterium sp. H13-3, offers promising insights into phage-host interactions. Using single particle analysis (SPA) cryo-electron microscopy (cryo-EM), we determined the capsid and tail structure, and built atomic models of capsid hexamers, pentamers and tail. Combined with cryo-electron tomography (cryo-ET) and machine learning methodologies, our findings indicate that phage 7-7-1 uses capsid fibers to establish initial contact with the host flagellum, followed by subsequent attachment to cell surface receptors. Proteinase K treatment confirmed the time-dependent degradation of capsid fibers. The study also demonstrated that capsid fibers are flexible and can interact with other phages and host flagella, suggesting a cooperative infection strategy. These results provide crucial structural insights and may open avenues for developing phage-based therapeutics against resistant bacterial pathogens.

microbiology↗

bioRxiv2023

CslA and GlxA from Streptomyces lividans form a functional cellulose synthase complex

Filamentous growth of streptomycetes coincides with the synthesis and deposition of an uncharacterized protective glucan at hyphal tips. Synthesis of this glucan depends on the integral membrane protein CslA and the radical copper oxidase GlxA, which are part of a presumably large multiprotein complex operating at growing tips. Here, we show that CslA and GlxA interact by forming a protein complex that is sufficient to synthesize cellulose in vitro. Mass spectrometry analysis revealed that the purified complex produces cellulose chains with a degree of polymerization of at least 80 residues. Truncation analyses demonstrated that the removal of a significant extracellular segment of GlxA had no impact on complex formation, but significantly diminished activity of CslA. Altogether, our work demonstrates that CslA and GlxA form the active core of the cellulose synthase complex and provides molecular insights into a unique cellulose biosynthesis system that is conserved in streptomycetes. SignificanceCellulose stands out as the most abundant polysaccharide on Earth. While the synthesis of this polysaccharide has been extensively studied in plants and Gram-negative bacteria, the mechanisms in Gram-positive bacteria have remained largely unknown. Our research unveils a novel cellulose synthase complex formed by the interaction between the cellulose synthase-like protein CslA and the radical copper oxidase GlxA from Streptomyces lividans, a soil-dwelling Gram-positive bacterium. This discovery provides molecular insights into the distinctive cellulose biosynthesis machineries. Beyond expanding our understanding of cellulose biosynthesis, this study also opens avenues for exploring biotechnological applications and ecological roles of cellulose in Gram-positive bacteria, thereby contributing to the broader field of microbial cellulose biosynthesis and biofilm research.

microbiology↗

bioRxiv2022

High resolution reconstruction of a Jumbo bacteriophage infecting capsulated bacteria using hyperbranched tail fibers

The Klebsiella jumbo myophage {phi}Kp24 displays an unusually complex arrangement of tail fibers interacting with a host cell. In this study, we combined cryo-electron microscopy methods, protein structure prediction methods, molecular simulations, and machine learning approaches to explore the capsid, tail, and tail fibers of this phage at high resolution. We determined the structure of the capsid and tail at 4.3[A] and 4.1[A] resolution. We observed that the tail fibers were highly branched and rearranged dramatically upon cell surface attachment. This complex configuration involves fourteen putative tail fibers with depolymerase activity that provide {phi}Kp24 with the ability to infect a broad panel of capsular polysaccharide (CPS) types of Klebsiella pneumoniae. Taken together, our study provides structural and functional insight into how {phi}Kp24 adapts to the highly variable surfaces of capsulated bacterial pathogens, which will be useful for the development of phage therapy approaches against pan-drug resistant K. pneumoniae strains.

microbiology↗

bioRxiv2020

Prohibitin protects against cigarette smoke extract-induced cell apoptosis in cultured human pulmonary microvascular endothelial cells

Prohibitin is an evolutionarily conserved and ubiquitously expressed protein in eukaryocyte. It mediate many important roles in cell survival, apoptosis, autophagy and senescence. In the present study, we aimed to explore the role of prohibitin in cigarette smoke extract (CSE)-induced apoptosis of human pulmonary microvascular endothelial cells (HPMECs). For this purpose, HPMECs were trasfected with prohibitin and challenged with CSE. Our results showed that CSE exposure inhibited prohibitin expression in a dose-dependent manner in HPMECs. Overexpression of prohibitin could protect cell from CSE-induced injury by inhibiting CSE-induced cell apoptosis, inhibiting reactive oxygen species (ROS) production, increase mitochondrial membrane potential, increase the content of mitochondrial transcription factor A (mtTFA), IKK/{beta} phosphorylation and I{kappa}B- degradation. CSE decreases prohibitin expression in endothelial cells and restoration of prohibitin expression in these cells can protect against the deleterious effects of CSE on mitochondrial and cells. We identified prohibitin is a novel regulator of endothelial cell apoptosis and survival in the context of cigarette smoke exposure.

pharmacology and toxicology↗