Allen Buskirk
Department of Molecular Biology and Genetics
Johns Hopkins University School of Medicine
714 Pre‐Clinical Teaching Building (PCTB)
725 N. Wolfe St
Baltimore, MD 21205
buskirk@jhmi.edu
The Buskirk group studies ribosome stalling and rescue in bacteria. In 2014 we moved to Hopkins to work with our long‐term collaborator Rachel Green who currently focuses on eukaryotic systems. Although the ribosome rescue mechanisms in bacteria and eukaryotes are quite different, we benefit from working together on shared fundamental questions and new experimental approaches. The bacterial studies in the Buskirk group continue to be supported by independent NIH funding.
Research Overview
Elongating ribosomes stall when they encounter damaged sites in mRNA or when decoding is slow because aminoacyl-tRNAs are in low abundance. In cases of prolonged stalling or arrest, ribosomes need to be removed and recycled. How do ribosome rescue pathways distinguish stalled ribosomes from actively translating ones?
We discovered that ribosome rescue in E. coli is triggered by collisions that occur when an upstream ribosome catches up to a stalled ribosome (Saito 2022). Collisions serve as a unique signal that something has gone wrong. They recruit an endonuclease, SmrB, that cleaves mRNAs upstream of the stall site. After the mRNA is cleaved, upstream ribosomes translate to the newly formed 3’-end where they are rescued quickly by tmRNA. In collaboration with Roland Beckmann’s lab in Munich, we obtained cryo-electron microscopy structures of collided disomes from E. coli and B. subtilis showing the distinct arrangements of individual ribosomes and revealing the composite SmrB-binding site.
Using genetics, biochemistry, and deep sequencing approaches, we continue to work on understanding the role that collisions play in preventing and resolving problems during protein synthesis in E. coli, B. subtilis, and other bacteria.
