Date of Completion


Embargo Period



Andrei T. Alexandrescu, Nathan N. Alder

Field of Study

Molecular and Cell Biology


Master of Science

Open Access

Open Access


The P22 coat protein has the HK97 fold at its core, but also has an additional domain on the surface of the capsid. Two recent cryo-EM structures at ~8 Å and ~4 Å resolution show different folds for this domain. The structure and function of this domain has been debated in the literature.

NMR spectroscopy was used to determine a high-resolution structure of this domain. Here, the domain is called the ‘insertion’ domain (I-domain). The structure is a six-stranded β-barrel with a small helix and belongs to a reductase/isomerase/elongation factor folding family.

Compared to the previous cryo-EM reconstructions, the NMR structure bears both similarities and differences. The core fold is different, but the NMR structure does resemble the 8 Å structure in its significant β-sheet content, and the 4 Å structure in the existence of a large loop (the D-loop). The function of the domain is still unresolved, although structural homology to domain II of eiF2-γ (a transcription factor that may bind tRNA) may be significant.

Major Advisor

Carolyn M. Teschke