ABSTRACT
One of the major goals of Alzheimer’s disease (AD) research is to understand how aging and the aggregation of
Aß and/or hyperphosphorylated Tau disrupt the proteostasis and cause progressive neuronal death. The current
paradigm of AD research focuses on the amyloid aggregation of Aß/Tau and the proteins sequestrated by these
aggregates. A key untouched question of proteostasis is whether the folding and conformation of soluble proteins,
which represent >99% of the proteome, are also changed during aging and AD. As protein conformation
determines the specific cellular function(s) of a given protein, the changes in protein folding and conformation
will disrupt the original protein functions or allow some polypeptides to acquire age-/AD-specific functions.
Nascent polypeptides take kinetically and thermodynamically favorable routes during de novo folding. The
energy landscape that determines the folding paths and final native conformations of a protein is shaped by the
physiochemical environment surrounding the nascent peptide. Using Saccharomyces cerevisiae (budding yeast)
as a model organism and a novel proteomics-structure pipeline, our preliminary studies revealed that changing
the cellular folding environment induces the alternative folding of many proteins. As changes in the proteome
composition and metabolic profile, two key components of the cellular folding environment, are conserved
hallmarks of aging and AD, the goal of this proposal is to understand how aging and AD affect the folding and
conformation of the soluble proteins. We propose to use budding yeast for this pilot project as it is a common
model organism used to study cellular and molecular mechanisms of aging. Yeast shares numerous biological
processes with animals and develops age-related cellular dysfunctions similar to human aging. In addition, the
yeast model of AD has been developed to reveal conserved mechanisms of amyloid aggregation and the cellular
toxicity of Aß and Tau. Aging is the major risk factor of AD and other age-related dementias. However, previous
studies looked at the young yeast cells expressing human Aß/Tau proteins. In this proposed project, we want to
combine the strength of aging and AD research in yeast to find alternative protein folding induced by Aß42/Tau
in aged cells. We intend to accomplish our goal by 1) determining the prevalence of protein alternative folding
induced by aging, and 2) dissecting the effect of Aß42/Tau on protein folding in aged cells. The hits from our
project will be a resource for researchers in the field to determine the gain or loss of protein functions associated
with these alternative folding of proteins. This work is expected to reveal the first 3D view of the proteome affected
by aging and Aß42/Tau.