Modell Lab
Principal Investigator: Joshua Modell
Institution: Johns Hopkins University (Baltimore, MD)
Primary Subfield: Molecular & Cell Bio
Recruitment Status: ✅ Accepting PhD Students ✅ Hiring Postdocs
Research Focus
Project Summary/Abstract Bacterial populations exhibit remarkable adaptability to diverse stresses, including fluctuating temperature, nutrient scarcity, oxidative challenges, and exposure to antibiotics and bacteriophages. A key survival strategy often involves rare cells that can resist or tolerate the stress, even while the majority of the population dies. These survivors can subsequently repopulate their niche and complicate efforts at eradication, exemplified by antibiotic-resistance, persistence, sporulation, and phase-variable expression of surface proteins. We study this phenomenon in the context of bacterial CRISPR-Cas adaptive immune systems. During an encounter with a new phage, one in a million infected cells can capture a 30bp segment of the phage DNA and store it as an immunological memory within the CRISPR array. These memories or “spacers” are transcribed into guide RNAs that provide immunity by directing Cas effectors to cleave matching targets during a subsequent infection. The molecular processes that allow cells to acquire a new spacer have long been a mystery, owing in part to the difficulties inherent in studying such rare immunization events. Using genomic sc…
Active NIH Awards
- 2R35GM142731-06: Mechanisms, regulation, and cell biology of rare CRISPR-Cas9 immunization events (2026)
- 5R35GM142731-05: Non-canonical functions of Cas9 andthe cell biology of CRISPR-Cas immunity (2025)
- 5R35GM142731-04: Non-canonical functions of Cas9 andthe cell biology of CRISPR-Cas immunity (2024)
- 3R35GM142731-04S1: Non-canonical functions of Cas9 andthe cell biology of CRISPR-Cas immunity (2024)
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