Adam started off his scientific journey at Oakland University, a small liberal arts college in Michigan. Oakland was a rich source of undergraduate research and allowed many opportunities such as: summer fellowships, grants during the semester and one on one time with a PI. John Finke guided Adam to his first 3 years of research studying amyloid proteins via SPR before moving on to the University of Michigan’s Program in Chemical Biology. After rotations Adam joined the lab of Daniel Southworth, an electron microscope expert to work on determining the structures of large protein complexes with a focus on molecular chaperones. With 4 years of work in the Southworth lab complete, Adam plans on graduating in 2017 and moving into a new chapter of scientific research. In addition to science, Adam’s hobbies include great Michigan beer, running and Game of Thrones.
Asymmetric spiral architecture of the hsp104 disaggregase revealed by cryo-EM.
The heat shock protein (Hsp) 100s are a class of conserved AAA+ protein disaggregases that form hexameric ring complexes and funnel substrates through a central channel to re-solubilize proteins for re-folding or proteolysis. Bacterial ClpB and Yeast Hsp104 collaborate with the Hsp70 and Hsp40 chaperone system to promote thermotolerance by rescuing stress-induced disordered aggregates. Hsp104, in particular, recognizes cross-beta structures of amyloid fibrils, such as those found in Sup35 prions, for dissolution to facilitate prion inheritance in yeast. Hsp104 contains four conserved domains: an N-terminal domain (NTD), involved in substrate recognition, two distinct AAA+ domains (NBD1 and NBD2) that bind polypeptides and power disaggregation, a middle domain (MD) that interacts with Hsp70 and regulates hydrolysis, as well as a unique C-terminal (CTD) that is required for hexamerization. Despite tremendous effort, structural models for how the Hsp104 hexamer functions have been limited, arguably to due to the flexibility and dynamics of the hexamer. Here we have performed an extensive cryo-electron microscopy (cryo-EM) structural analysis of the Hsp104 wildtype complex and determined a reconstruction to an unprecedented 5.6 angstrom resolution. Remarkably, we identify that Hsp104 adopts an asymmetric spiral architecture and the substrate binding “pore loops” line the axial channel in a distinct staggered arrangement that connects the NBD1 and NBD2 domains. This structure explains how Hsp104, and likely other conserved family members, coordinate the power of 12 ATPase domains to drive polypeptide translocation during disaggregation.