Science Workshop: Joe Kendrick, Elsa Costa

When: Back to Calendar May 9, 2014 @ 1:00 pm - 2:00 pm
Where: Dickinson 225
Categories:
Science Workshops

Join us for Joe Kendrick’s and Elsa Costa’s presentations on their advanced work projects. Details below.

Joe Kendrick:
Explaining variation in soil respiration in young, patchy forests

 Soil respiration is one of the most important pathways by which carbon dioxide is released from terrestrial ecosystems to the atmosphere. In temperate forests, the rate of respiration can vary tremendously even at a very small scale. In this study, I seek to explain the reason for this variation. I explore interactions between several important ecosystem and community properties and the extent to which they shape both the observed rate of respiration and its temperature dependence. In doing so, I question some key assumptions often made by ecosystem ecologists studying soil respiration.

 

Elsa Costa:
Trp5p May Assist In Ubiquitin-Mediated Proteasomal Degradation of Misfolded Protein

The ubiquitin-proteasome system forms one of the main mechanisms of unregulated protein degradation. While some proteins are scheduled for regular turnover according to a set pathway in regulated degradation, unregulated degradation occurs in the event of an error in protein folding or other irregularity in the protein structure. In the ubiquitin-proteasome system, a ubiquitin-activating enzyme (E1) prepares ubiquitin to attach to the protein, while a ubiquitin-protein ligase (E3) binds the substrate. The ubiquitin-conjugating enzyme (E2)  then transfers the E1 to the E3, and the latter catalyzes the covalent attachment of ubiquitin to the substrate, marking the substrate for degradation by the proteasome. The binding location of the substrate is of particular interest, as E3s seem universally to pick out misfolded proteins in unregulated proteolysis, and the question of what is common to all misfolded proteins, whatever their normative structure, arises. In fact, artificial degradation signals can be engineered and bound to proteins, triggering their degradation; hydrophobic stretches and amphipathic alpha helices have been revealed to induce degradation, and have been demonstrated explicitly to bind with many E3 ligases. These artificial degradation signals, or degrons, transformed with a protein, can be used to reveal the particular mechanisms of its degradation. By removing certain genes suspected to be influential in the process of proteolysis, it becomes possible to isolate which of the proteins corresponding to those genes are necessary to degradation of the studied protein, both within and without the ubiquitin-proteasome system. This project focuses on a gene — trp5 (coding for tryptophan synthase) — not previously known to play a part in the ubiquitin-proteasome  system, and the experimental contexts in which its absence has been shown to inhibit protein degradation.

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