Bio

Dr. Naima Gabriela Sharaf graduated from the University of North Carolina at Chapel Hill with a bachelor's degree in chemistry. She earned her Ph.D. in Dr. Angela Gronenborn's lab at the University of Pittsburgh, where she investigated inhibitor-induced conformational changes in HIV-1 reverse transcriptase using fluorine solution NMR. She completed her postdoctoral training at Caltech in Dr. Doug Rees' lab, where she used x-ray crystallography and single-particle cryo-EM to characterize the structure and function of the Neisseria meningitidis methionine ABC transport system. This study sparked Dr. Sharaf's current interest in lipoproteins, specifically their roles in bacterial physiology and potential in vaccine design. The Sharaf Lab conducts research that bridges biochemistry, biology, microbiology, and immunology in order to translate lipoprotein research into therapeutics.

Keywords: Biochemistry, bioengineering, biophysics, biotechnology, drug discovery, microbiology, protein engineering, structural biology, x-ray crystallography, cryoEM, nanoparticles

Academic Appointments

Contact

Additional Info

Links

Current Research and Scholarly Interests

Bacterial lipoproteins are characterized by a covalently attached lipid moiety that anchors the protein to cellular membranes. In bacteria, these lipoproteins play key roles in bacterial physiology, including signaling, nutrient acquisition, and host-pathogen interactions. Our lab is divided into two research areas related to lipoproteins:

Area 1: To characterize the structure and function of bacterial lipoproteins in the bacterium Borrelia burgdorferi, the causative agent of Lyme disease.


Area 2: To develop and characterize lipoprotein-based nanoparticles, materials, and therapeutics.


Keywords: Biochemistry, bioengineering, biophysics, biotechnology, drug discovery, microbiology, protein engineering, structural biology, x-ray crystallography, cryoEM, nanoparticles

2024-25 Courses

Stanford Advisees

All Publications

  • Expression, purification, and characterization of diacylated Lipo-YcjN from Escherichia coli. The Journal of biological chemistry Trevino, M. A., Amankwah, K. A., Fernandez, D., Weston, S. A., Stewart, C. J., Gallardo, J. M., Shahgholi, M., Sharaf, N. G. 2024: 107853

    Abstract

    YcjN is a putative substrate binding protein expressed from a cluster of genes involved in carbohydrate import and metabolism in Escherichia coli. Here, we determine the crystal structure of YcjN to a resolution of 1.95 A, revealing that its three-dimensional structure is similar to substrate binding proteins in subcluster D-I, which includes the well-characterized maltose binding protein (MBP). Furthermore, we found that recombinant overexpression of YcjN results in the formation of a lipidated form of YcjN that is posttranslationally diacylated at cysteine 21. Comparisons of size-exclusion chromatography profiles and dynamic light scattering measurements of lipidated and non-lipidated YcjN proteins suggest that lipidated YcjN aggregates in solution via its lipid moiety. Additionally, bioinformatic analysis indicates that YcjN-like proteins may exist in both Bacteria and Archaea, potentially in both lipidated and non-lipidated forms. Together, our results provide a better understanding of the aggregation properties of recombinantly expressed bacterial lipoproteins in solution and establish a foundation for future studies that aim to elucidate the role of these proteins in bacterial physiology.

    View details for DOI 10.1016/j.jbc.2024.107853

    View details for PubMedID 39362470

  • Characterization of the ABC methionine transporter from Neisseria meningitidis reveals that lipidated MetQ is required for interaction ELIFE Sharaf, N. G., Shahgholi, M., Kim, E., Lai, J. Y., VanderVelde, D. G., Lee, A. T., Rees, D. C. 2021; 10

    Abstract

    NmMetQ is a substrate-binding protein (SBP) from Neisseria meningitidis that has been identified as a surface-exposed candidate antigen for meningococcal vaccines. However, this location for NmMetQ challenges the prevailing view that SBPs in Gram-negative bacteria are localized to the periplasmic space to promote interaction with their cognate ABC transporter embedded in the bacterial inner membrane. To elucidate the roles of NmMetQ, we characterized NmMetQ with and without its cognate ABC transporter (NmMetNI). Here, we show that NmMetQ is a lipoprotein (lipo-NmMetQ) that binds multiple methionine analogs and stimulates the ATPase activity of NmMetNI. Using single-particle electron cryo-microscopy, we determined the structures of NmMetNI in the presence and absence of lipo-NmMetQ. Based on our data, we propose that NmMetQ tethers to membranes via a lipid anchor and has dual function and localization, playing a role in NmMetNI-mediated transport at the inner membrane and moonlighting on the bacterial surface.

    View details for DOI 10.7554/eLife.69742

    View details for Web of Science ID 000693095000001

    View details for PubMedID 34409939

    View details for PubMedCentralID PMC8416018

https://orcid.org/0000-0002-3662-9228