For those interested in joining our Lab, please visit the OPEN POSITIONS page for more information!

Farshad Abdollah-Nia, Ph.D., Postdoctoral Fellow
I am interested in understanding how bacterial cells manage the production of proteins, as well as the flux of metabolites in different growth conditions. I use mass spectrometry to quantify protein levels on a cell-wide scale in E. coli. Then I apply mathematical models that describe the dynamics of large groups of proteins. These models help us understand global resource allocation strategies in cells and enable us to predict the growth and the makeup of the cells in various environments.
Anshul Chaudhary, Ph.D., Postdoctoral Associate
I am focusing on understanding ribosome biogenesis. RNA helicases play various roles in ribosome biogenesis; however, it is unclear how most RNA helicases interact with intermediates of ribosome assemblies. SrmB is a DEAD-box helicase that operates early in the ribosome assembly process. To provide a structural and functional view of SrmB, DEAD-box helicase for ribosome assembly, this study uses a range of biochemical, biophysical, and X-ray/cryo-electron techniques.
xiyuXiyu Dong, B.S., Graduate Student
My interest is in bacterial ribosome biogenesis. Ribosome assembly is a complicated but rapid process in vivo. An in vitro ribosome reconstruction system can slow this process and provide the insights into the mechanism of ribosome assembly. I’m now working on the visualization of incomplete ribosome particles with cryo-EM. Besides, I’m also interested in identifying RNA modifications in bacteria by quantitative mass spectrometry.
John Hammond, Ph.D., Biophysics Core Director
I am interested in the assembly, function, and structure of viral/host ribonucleoprotein complexes. Of late, we have been studying the assembly of a nuclear export complex required for HIV-1 replication, as well as understanding the assembly of the HIV-1 virus. This work uses a variety of biochemical, biophysical and cellular biology techniques to provide a universal structural and functional view of these RNP processes.
Joan LeeJoan Lee, B.S., Research Assistant
I earned a B.S. in Biochemistry/Chemistry from the University of California, San Diego, and graduated with the highest departmental honors. During my undergraduate research, I studied the binding affinity between NFκB and transcription coactivators, such as ribosomal protein S3, and their binding affinity with various DNA. I am currently studying ribosomal intermediates in E.coli using cryo-electron tomography in the Williamson and Grotjahn Labs.
Aliya ParachaAliya Paracha, B.S., Research Assistant
I graduated from University of California, San Diego with a B.S. in Cognitive Science and a minor in Computer Science. I am interested in understanding the role of RNA modifications in brain and behavior. I am also an aspiring Neuroscientist and will be pursuing my Ph.D. as my stepping stone.
Anna Popova, Ph.D., Staff Scientist
I am particularly fond of rRNA modifications! All different kinds, found in bacteria, yeast, and human cells. Using modern mass spectrometry tools, I can identify and quantify relative abundance of RNA modifications in mature ribosomes and the intermediates. This quantitative approach proved to be effective in understanding modifications as part of the ribosome biogenesis process.
LinkedIn | ResearchGate
Katrina Schreiber, Administrative Manager
Analytical and detail-oriented professional with experience coordinating, planning, and supporting daily operational and administrative functions within the Williamson Laboratory and in support of Dr. Williamson’s executive obligations. Katrina comes from a lengthy background of management roles in research and healthcare, with 21+ combined years at Scripps, and plans to continue her lifelong pursuit of assisting her colleagues, so they can focus on what they do best…science!
Resume | LinkedIn
Lincoln Scott, Ph.D., Visiting Investigator
I am interested in the chemo-enzymatic synthesis of isotopically labeled nucleotides and nucleotide analogs. These compounds are used in a variety of NMR and mass spectrometry based biophysical studies of RNA and RNA-protein complexes. This work has led to the formation of Cassia LLC, a company that prepares isotopically labeled primary metabolites for the biophysical research community.
Cassia, LLC | LinkedIn | ResearchGate
Kai Sheng, B.S., Graduate Student
I was trained as a chemical biologist during my undergraduate research, developing methodology in protein modifications and its applications in therapeutics. I also had one year working with Floyd Romesberg, exploring the exciting semi-synthetic organism. Now I turned my research interest to ribosomes, one of the most beautiful, sophisticated and meanwhile complex systems in biology. I am now using the in vitro ribosome assembly assay to screen inhibitors which are specific for the assembling process.
Marina Youngblood, B.S., Research Assistant
Marina earned her BSc in Cellular and Molecular Biology from the University of La Verne and graduated from the Honors Program. She conducted her senior thesis research in the lab of Stacey Darling-Novak where she studied first leaf formation in S. plicata identifying novel auxin-mediated genes.
Marina spent four years in industry at Lumos Diagnostics, Cibus and the San Diego County Public Health Lab before joining the Grotjahn and Williamson labs. The labs began their collaboration in 2019 and Marina is currently using cryo-electron tomography to visualize ribosomal intermediates in E.coli. She is also an aspiring plant biologist applying to PhD programs. Outside of research, Marina loves to spend time with her cats, make pies, camp, compost, and grow odd vegetables. 
Anne Zhou, B.S., Graduate Student
I am working on elucidating stepwise Gag assembly process in the presence of both lipids and RNAs. To accomplish this goal, we are looking into using nanodisc combined with single molecule TIRF technology to facilitate our observations. We aim to investigate how Gag comes into association with viral RNA and membrane lipids, how different Gag or RNA mutations would affect the assembly process, and how membrane lipids composition may play a role and to what extent.

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