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Limited Functional Redundancy And Oscillation Of Cyclins In Multinucleated Ashbya Gossypii Fungal Cells, A. Katrin Hungerbuehler, Peter Philippsen, Amy S. Gladfelter Nov 2006

Limited Functional Redundancy And Oscillation Of Cyclins In Multinucleated Ashbya Gossypii Fungal Cells, A. Katrin Hungerbuehler, Peter Philippsen, Amy S. Gladfelter

Dartmouth Scholarship

Cyclin protein behavior has not been systematically investigated in multinucleated cells with asynchronous mitoses. Cyclins are canonical oscillating cell cycle proteins, but it is unclear how fluctuating protein gradients can be established in multinucleated cells where nuclei in different stages of the division cycle share the cytoplasm. Previous work in A. gossypii, a filamentous fungus in which nuclei divide asynchronously in a common cytoplasm, demonstrated that one G1 and one B-type cyclin do not fluctuate in abundance across the division cycle. We have undertaken a comprehensive analysis of all G1 and B-type cyclins in A. gossypii to determine whether …


Erv26p Directs Pro-Alkaline Phosphatase Into Endoplasmic Reticulum–Derived Coat Protein Complex Ii Transport Vesicles, Catherine A. Bue, Christine M. Bentivoglio, Charles Barlowe Sep 2006

Erv26p Directs Pro-Alkaline Phosphatase Into Endoplasmic Reticulum–Derived Coat Protein Complex Ii Transport Vesicles, Catherine A. Bue, Christine M. Bentivoglio, Charles Barlowe

Dartmouth Scholarship

Secretory proteins are exported from the endoplasmic reticulum (ER) in transport vesicles formed by the coat protein complex II (COPII). We detected Erv26p as an integral membrane protein that was efficiently packaged into COPII vesicles and cycled between the ER and Golgi compartments. The erv26Δ mutant displayed a selective secretory defect in which the pro-form of vacuolar alkaline phosphatase (pro-ALP) accumulated in the ER, whereas other secretory proteins were transported at wild-type rates. In vitro budding experiments demonstrated that Erv26p was directly required for packaging of pro-ALP into COPII vesicles. Moreover, Erv26p was detected in a specific complex with pro-ALP …


Bounded Search For De Novo Identification Of Degenerate Cis-Regulatory Elements, Jonathan M. Carlson, Arijit Chakravarty, Radhika S. Khetani, Robert H. Gross May 2006

Bounded Search For De Novo Identification Of Degenerate Cis-Regulatory Elements, Jonathan M. Carlson, Arijit Chakravarty, Radhika S. Khetani, Robert H. Gross

Dartmouth Scholarship

The identification of statistically overrepresented sequences in the upstream regions of coregulated genes should theoretically permit the identification of potential cis-regulatory elements. However, in practice many cis-regulatory elements are highly degenerate, precluding the use of an exhaustive word-counting strategy for their identification. While numerous methods exist for inferring base distributions using a position weight matrix, recent studies suggest that the independence assumptions inherent in the model, as well as the inability to reach a global optimum, limit this approach.


Structural And Function Analyses Of The Global Regulatory Protein Sara From Staphylococcus Aureus, Yingfang Liu, Adhar C. Manna, Cheol-Ho Pan, Irina A. Kriksunov Feb 2006

Structural And Function Analyses Of The Global Regulatory Protein Sara From Staphylococcus Aureus, Yingfang Liu, Adhar C. Manna, Cheol-Ho Pan, Irina A. Kriksunov

Dartmouth Scholarship

The sarA locus in Staphylococcus aureus controls the expression of many virulence genes. The sarA regulatory molecule, SarA, is a 14.7-kDa protein (124 residues) that binds to the promoter region of target genes. Here we report the 2.6 Å-resolution x-ray crystal structure of the dimeric winged helix SarA protein, which differs from the published SarA structure dramatically. In the crystal packing, multiple dimers of SarA form a scaffold, possibly via divalent cations. Mutations of individual residues within the DNA-binding helix–turn–helix and the winged region as well as within the metal-binding pocket implicate basic residues R84 and R90 within the winged …


A Pdz-Binding Motif As A Critical Determinant Of Rho Guanine Exchange Factor Function And Cell Phenotype, Miaoliang Liu, Arie Horowitz Feb 2006

A Pdz-Binding Motif As A Critical Determinant Of Rho Guanine Exchange Factor Function And Cell Phenotype, Miaoliang Liu, Arie Horowitz

Dartmouth Scholarship

We identified a Rho guanine exchange factor (GEF) expressed as two splice variants, which differ only in either having or lacking a Postsynaptic density 95, Disk large, Zona occludens-1 (PDZ) motif. The PDZ adaptor protein synectin bound the longer splice variant, Syx1, which was targeted to the plasma membrane in a synectin-dependent manner. The shorter variant, Syx2, was diffusely distributed in the cytoplasm. Fluorescence resonance energy transfer (FRET) imaging revealed similar differences between the spatial patterns of active RhoA in Syx1 versus Syx2-expressing cells. Expression of Syx1 augmented endothelial cell (EC) migration and tube formation, whereas Syx2 expression did not. …


Rab-10 Is Required For Endocytic Recycling In The Caenorhabditis Elegans Intestine, Carlos Chih-Hsiung Chen, Peter J. Schweinsberg, Shilpa Vashist, Darren P. Mareiniss, Eric J. Lambie, Barth D. Grant Jan 2006

Rab-10 Is Required For Endocytic Recycling In The Caenorhabditis Elegans Intestine, Carlos Chih-Hsiung Chen, Peter J. Schweinsberg, Shilpa Vashist, Darren P. Mareiniss, Eric J. Lambie, Barth D. Grant

Dartmouth Scholarship

The endocytic pathway of eukaryotes is essential for the internalization and trafficking of macromolecules, fluid, membranes, and membrane proteins. One of the most enigmatic aspects of this process is endocytic recycling, the return of macromolecules (often receptors) and fluid from endosomes to the plasma membrane. We have previously shown that the EH-domain protein RME-1 is a critical regulator of endocytic recycling in worms and mammals. Here we identify the RAB-10 protein as a key regulator of endocytic recycling upstream of RME-1 in polarized epithelial cells of the Caenorhabditis elegans intestine. rab-10 null mutant intestinal cells accumulate abnormally abundant RAB-5-positive early …


Innate Antiviral Response Targets Hiv-1 Release By The Induction Of Ubiquitin-Like Protein Isg15, Atsushi Okumura, Gengshi Lu, Ian Pitha-Rowe, Paula M. Pitha Jan 2006

Innate Antiviral Response Targets Hiv-1 Release By The Induction Of Ubiquitin-Like Protein Isg15, Atsushi Okumura, Gengshi Lu, Ian Pitha-Rowe, Paula M. Pitha

Dartmouth Scholarship

The goal of this study was to elucidate the molecular mechanism by which type I IFN inhibits assembly and release of HIV-1 virions. Our study revealed that the IFN-induced ubiquitin-like protein ISG15 mimics the IFN effect and inhibits release of HIV-1 virions without having any effect on the synthesis of HIV-1 proteins in the cells. ISG15 expression specifically inhibited ubiquitination of Gag and Tsg101 and disrupted the interaction of the Gag L domain with Tsg101, but conjugation of ISG15 to Gag or Tsg101 was not detected. The inhibition of Gag-Tsg101 interaction was also detected in HIV-1 infected, IFN-treated cells. Elimination …