Host-derived small RNAs are emerging as critical regulators in the dynamic interactions between host tissues and the microbiome, with implications for microbial pathogenesis and host defense. Among these, transfer RNA-derived small RNAs (tsRNAs) have garnered attention for their roles in modulating microbial behavior. However, the bacterial factors mediating tsRNA interaction and functionality remain poorly understood. In this study, using RNA affinity pull-down assay in combination with mass spectrometry, we identified a putative membrane-bound protein, annotated as P-type ATPase transporter (PtaT) in Fusobacterium nucleatum (Fn), which binds Fn-targeting tsRNAs in a sequence-specific manner. Through targeted mutagenesis and phenotypic characterization, we showed that in both the Fn type strain and a clinical tumor isolate, deletion of ptaT led to reduced tsRNA intake and enhanced resistance to tsRNA-induced growth inhibition. Global RNA sequencing and label-free Raman spectroscopy revealed the phenotypic differences between Fn wild type and PtaT-deficient mutant, highlighting the functional significance of PtaT in purine and pyrimidine metabolism. Furthermore, AlphaFold 3 prediction provides evidence supporting the specific binding between PtaT and Fn-targeting tsRNA. By uncovering the first RNA-binding protein in Fn implicated in growth modulation through interactions with host-derived small RNAs (sRNAs), our study offers new insights into sRNA-mediated host-pathogen interplay within the context of microbiome-host interactions.
Fusobacterium nucleatum/growth & development* ; RNA-Binding Proteins/genetics* ; Bacterial Proteins/genetics* ; RNA, Bacterial/metabolism* ; Humans ; RNA, Transfer/metabolism*

Fusobacterium nucleatum (Fn) is an oral anaerobic bacterium that has recently been found to colonize on the surface of colorectal cancer cells in humans, and its degree of enrichment is highly negatively correlated with the prognosis of tumor treatment. Numerous studies have shown that Fn is involved in the occurrence and development of colorectal cancer (CRC), and Fn interacts with multiple components in the tumor microenvironment to increase tumor resistance. In recent years, researchers have begun using nanomedicine to inhibit Fn's proliferation at the tumor site or directly target Fn to treat CRC. This review summarizes the mechanism of Fn in promoting CRC and the latest research progress on Fn-related CRC therapy using different nanomaterials. Finally, the applications perspective of nanomaterials in Fn-promoted CRC therapy was prospected.
Humans ; Colorectal Neoplasms/pathology* ; Fusobacterium nucleatum/genetics* ; Base Composition ; RNA, Ribosomal, 16S ; Phylogeny ; Sequence Analysis, DNA ; Tumor Microenvironment

Fusobacterium nucleatum is an opportunistic pathogenic bacterium that can be enriched in colorectal cancer tissues, affecting multiple stages of colorectal cancer development. The two-component system plays an important role in the regulation and expression of genes related to pathogenic resistance and pathogenicity. In this paper, we focused on the CarRS two-component system of F. nucleatum, and the histidine kinase protein CarS was recombinantly expressed and characterized. Several online software such as SMART, CCTOP and AlphaFold2 were used to predict the secondary and tertiary structure of the CarS protein. The results showed that CarS is a membrane protein with two transmembrane helices and contains 9 α-helices and 12 β-folds. CarS protein is composed of two domains, one is the N-terminal transmembrane domain (amino acids 1-170), the other is the C-terminal intracellular domain. The latter is composed of a signal receiving domain (histidine kinases, adenylyl cyclases, methyl-accepting proteins, prokaryotic signaling proteins, HAMP), a phosphate receptor domain (histidine kinase domain, HisKA), and a histidine kinase catalytic domain (histidine kinase-like ATPase catalytic domain, HATPase_c). Since the full-length CarS protein could not be expressed in host cells, a fusion expression vector pET-28a(+)-MBP-TEV-CarS_cyto was constructed based on the characteristics of secondary and tertiary structures, and overexpressed in Escherichia coli BL21-Codonplus(DE3)RIL. CarS_cyto-MBP protein was purified by affinity chromatography, ion-exchange chromatography, and gel filtration chromatography with a final concentration of 20 mg/ml. CarS_cyto-MBP protein showed both protein kinase and phosphotransferase activities, and the MBP tag had no effect on the function of CarS_cyto protein. The above results provide a basis for in-depth analysis of the biological function of the CarRS two-component system in F. nucleatum.
Humans ; Histidine Kinase/metabolism* ; Fusobacterium nucleatum/metabolism* ; Automobiles ; Protein Kinases/genetics* ; Escherichia coli/metabolism* ; Colorectal Neoplasms