Skip to content Skip to sidebar Skip to footer

Friday, April 14th
4:30 pm
106 Stanley Hall

Speaker 1: Adam M. Perez (Jeremy Thorner lab)

The role of the septin cytoskeleton in the control of the yeast cell cycle

Septins are a conserved family of Eukaryotic cytoskeletal elements. These proteins are small GTPases that self-polymerize into heteromeric rods, which serve as the base building units of diverse septin super-structures. In the cell, septin architectures play essential roles in many biological processes, including cytokinesis, membrane remodeling, morphogenesis, and cell-cycle regulation. Septins accomplish these feats in part by serving as a scaffold that recruits a host of downstream effectors to sub-cellular sites in response to upstream inputs. In the budding yeast Saccharomyces cerevisiae, septins assemble into a filamentous network at the future site of cytokinesis. There, the septins act as a platform on which many proteins that drive cell septation assemble. Also recruited to the septin filaments are a host of signaling enzymes that serve to couple cell division with cell cycle progression. While the integrity of the septin cytoskeleton is required for recruitment of these proteins and for cytokinesis to occur, little is known about the mechanisms of the interactions of septins with downstream proteins. One attractive model by which septins dynamically recruit proteins to the bud neck of the yeast cell is via post translational modifications to various septin subunits. One protein that localizes to the bud neck, Nis1, has been found to contain a motif that interacts with the small modifier of ubiquitin, SUMO, or Smt3 in budding yeast. Curiously, the septins are heavily, and only briefyly, SUMOylated before mitosis. We are undertaking genetic and fluorescent micscroscopy experiments in vivo as well as in vitro binding assays to interrogate the role of septin SUMOylation in the control of their interaction with Nis1. In parallel, we have performed a genome wide screen using saturated transposon analysis (SATAY) to identify factors that interact genetically with Nis1 to control of the yeast cell cycle. Our findings suggest that Nis1 may play a role in transmitting cell cycle cues from the nucleus and mitochondria to the septin cytoskeleton at the bud neck, and thus act as a novel regulator of cytokinesis.

Speaker 2: Raúl H. Lavorie (T. Don Tilley lab) 

Artificial metalloproteins with Co4(µ3-O)4 cubanes as active sites. Towards a molecular and electronic control using a protein as a host.

The biological energy intake in photosynthetic systems involves a distorted Mn4O5Ca cubane as active site for the water oxidation reaction. Whereas, synthetic systems that perform this reaction are metal oxides that feature cubane oxo structural motives. In this context, Co4(µ3-O)4 cubanes are used as molecular models of cobalt oxide for the oxygen evolution reaction (OER).  These platforms are possible to substitute with different ligands in order modify its redox behavior or attach tailoring motives. This work presents the efforts to use a proteic environment to tune the reactivity of a molecular OER catalyst using the biotin-streptavidin technology.