Molecular Determinants of Nascent Protein Fate

overviewProtein biosynthesis is complex. To function properly, new proteins must be accurately synthesized from mRNA, fold into specific three-dimensional structures, undergo posttranslational modifications, assemble into multi-component complexes, and localize to the correct cellular destination. Each step of protein biosynthesis is closely monitored by regulatory and quality control processes that are essential for maintaining cellular homeostasis and preventing various human diseases. We aim to dissect the molecular mechanisms that determine the fate of nascent proteins using strategies that incorporate biochemistry, cell biology, and structural biology.

Our approaches include:

  1. Reconstituting protein biosynthesis and quality control processes using cell culture, in vitro lysate-based, and completely purified experimental systems.
     
  2. Developing methods and generating reagents to identify, uncouple, and mechanistically dissect the individual steps and molecular components of these cellular pathways.
     
  3. Isolating or assembling biologically-relevant macromolecular complexes that represent functional intermediates of these pathways for structural analysis, primarily via single-particle electron cryomicroscopy (cryo-EM).

Tail-Anchored Protein Triage

Newly synthesized proteins should be given protected time to mature, but be promptly degraded if they fail. We use the biosynthesis, sorting, and quality control of tail-anchored (TA) membrane proteins as a model to study the mechanisms underlying protein triage decisions.

Stop Codon Recognition

Three universal stop codons (UAA, UGA, UAG) signal for the termination of protein synthesis in almost all organisms. We use in vitro reconstitution and high-resolution cryo-EM to study how the context of stop codons influences translation termination events in eukaryotes.

Molecular Recognition of Translational Arrest

Ribosomes that stall while synthesizing new proteins recruit dedicated factors to rescue the arrested ribosome, signal for wider cellular responses, and determine the fate of the mRNA and nascent protein. We aim to understand the molecular mechanisms that specifically recognize differently stalled ribosomes and mediate these downstream consequences.