Qianqiao Liu

All Publications

• LipoLoad:RB: a nanocarrier comprising bacterial lipoprotein LipoMetQ and Rose Bengal. Scientific reports Liu, Q., Arslanian, M. A., Treviño, M. A., Quispe Calla, N. E., Starvaggi, F., Sharaf, N. G. 2026

  Abstract

  While conventional nanocarriers like liposomes are effective for small-molecule delivery, their fabrication often involves complex, multi-step processes. This work provides a proof-of-concept demonstrating a bacterial lipoprotein as a viable, genetically encoded, and self-assembling nanocarrier. We show specifically that the detergent-solubilized lipoprotein LipoMetQ from Neisseria meningitidis spontaneously forms micelle-like nanoparticles (termed LipoLoad), which entrap the small molecule Rose Bengal (RB) using a simple procedure of mixing and centrifugal ultrafiltration. The resulting LipoLoad: RB formulation was analyzed by dynamic light scattering and negative-stain TEM. Entrapment was found to decrease RB aggregation and enable a sustained release profile in vitro relative to the free drug. Furthermore, MTT assays performed on a subset of cancer cell lines revealed that LipoLoad: RB increased the intrinsic cytotoxic activity of RB. These results establish LipoLoad as a novel, biologically encoded nanocarrier. The facile production method, which does not require specialized equipment, and the formulation's stability underscore the broad potential of bacterial lipoproteins as a modular platform for nanotechnology.

  View details for DOI 10.1038/s41598-026-61887-8

  View details for PubMedID 42436244

• Structural basis for selective thymidine binding by the Borrelia burgdorferi substrate-binding protein BmpA. The Journal of biological chemistry Liu, Q., Nun Ez, V. A., Fernandez, D., Stewart, C. J., Sharaf, N. G. 2026: 113206

  Abstract

  BmpA is a putative substrate-binding protein from Borrelia burgdorferi, the causative agent of Lyme disease, an organism with limited metabolic capacity that relies on salvage pathways rather than de novo nucleotide biosynthesis. Here, we determine the crystal structure of BmpA to a resolution of 2.6 Å, revealing a conserved substrate-binding protein fold with a deeply buried nucleoside-binding pocket. Using microscale thermophoresis, we show that BmpA binds thymidine with high affinity followed by cytidine and adenosine, whereas binding to ribose, guanosine, inosine, and uridine was not detected. Structure-guided mutagenesis further demonstrates that two conserved aromatic residues (Phe27 and Phe176) are essential for thymidine recognition, as alanine substitution at either position abolishes detectable binding. Additionally, a Foldseek-based structural homology search identified related proteins across diverse bacterial and archaeal species that share a conserved overall fold and binding-site architecture despite low sequence similarity, consistent with an evolutionarily conserved scaffold that can accommodate distinct nucleoside ligands. Together, our work illustrates how conserved binding protein architectures enable selective nucleoside acquisition and provides a foundation for understanding nutrient uptake strategies in organisms with reduced genomes.

  View details for DOI 10.1016/j.jbc.2026.113206

  View details for PubMedID 42208901

• Development of novel bacterial lipoprotein-based nanoparticle for Rose Bengal delivery Liu, Q., Arslanian, M. A., Trevino, M. A., Starvaggi, F., Sharaf, N. G. CELL PRESS. 2026

  View details for Web of Science ID 001717804800116

• Insights into nucleoside transport in lyme disease: structure and function of<i> Borrelia</i><i> Burgdorferi</i> Bmp proteins Liu, Q., Fernandez, D., Alexandrova, L., Sharaf, N. G. WILEY. 2025

  View details for Web of Science ID 001654266000214

• Crystal structure and ligand-binding specificity of the Borrelia burgdorferi proteins BmpA and BmpB Sharaf, N., Liu, Q., Fernandez, D. ELSEVIER. 2025

  View details for DOI 10.1016/j.jbc.2025.109939

  View details for Web of Science ID 001530451700093

• SIgA structures bound to Streptococcus pyogenes M4 and human CD89 provide insights into host-pathogen interactions. Nature communications Liu, Q., Stadtmueller, B. M. 2023; 14 (1): 6726

  Abstract

  Immunoglobulin (Ig) A functions as monomeric IgA in the serum and Secretory (S) IgA in mucosal secretions. Host IgA Fc receptors (FcalphaRs), including human FcalphaR1/CD89, mediate IgA effector functions; however, human pathogen Streptococcus pyogenes has evolved surface-protein virulence factors, including M4, that also engage the CD89-binding site on IgA. Despite human mucosa serving as a reservoir for pathogens, SIgA interactions with CD89 and M4 remain poorly understood. Here we report cryo-EM structures of M4-SIgA and CD89-SIgA complexes, which unexpectedly reveal different SIgA-binding stoichiometry for M4 and CD89. Structural data, supporting experiments, and modeling indicate that copies of SIgA bound to S. pyogenes M4 will adopt similar orientations on the bacterium surface and leave one host FcalphaR binding site open. Results suggest unappreciated functional consequences associated with SIgA binding to host and bacterial FcalphaRs relevant to understanding host-microbe co-evolution, IgA effector functions and improving the outcomes of group A Streptococcus infection.

  View details for DOI 10.1038/s41467-023-42469-y

  View details for PubMedID 37872175