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Full-Text Articles in Molecular Biology

Multiple Molecular Mechanisms Rescue Mtdna Disease In C. Elegans, Suraiya Haroon, Annie Li, Jaye L. Weinert, Clark Fritsch, Nolan G. Ericson, Jasmine Alexander-Floyd, Bart P. Braeckman, Cole M. Haynes, Jason H. Bielas, Tali Gidalevitz, Marc Vermulst Mar 2018

Multiple Molecular Mechanisms Rescue Mtdna Disease In C. Elegans, Suraiya Haroon, Annie Li, Jaye L. Weinert, Clark Fritsch, Nolan G. Ericson, Jasmine Alexander-Floyd, Bart P. Braeckman, Cole M. Haynes, Jason H. Bielas, Tali Gidalevitz, Marc Vermulst

University of Massachusetts Medical School Faculty Publications

Genetic instability of the mitochondrial genome (mtDNA) plays an important role in human aging and disease. Thus far, it has proven difficult to develop successful treatment strategies for diseases that are caused by mtDNA instability. To address this issue, we developed a model of mtDNA disease in the nematode C. elegans, an animal model that can rapidly be screened for genes and biological pathways that reduce mitochondrial pathology. These worms recapitulate all the major hallmarks of mtDNA disease in humans, including increased mtDNA instability, loss of respiration, reduced neuromuscular function, and a shortened lifespan. We found that these phenotypes could ...


An Arginine Finger Regulates The Sequential Action Of Asymmetrical Hexameric Atpase In The Double-Stranded Dna Translocation Motor, Zhengyi Zhao, Gian Marco De-Donatis, Chad T. Schwartz, Huaming Fang, Jingyuan Li, Peixuan Guo Oct 2016

An Arginine Finger Regulates The Sequential Action Of Asymmetrical Hexameric Atpase In The Double-Stranded Dna Translocation Motor, Zhengyi Zhao, Gian Marco De-Donatis, Chad T. Schwartz, Huaming Fang, Jingyuan Li, Peixuan Guo

Pharmaceutical Sciences Faculty Publications

Biological motors are ubiquitous in living systems. Currently, how the motor components coordinate the unidirectional motion is elusive in most cases. Here, we report that the sequential action of the ATPase ring in the DNA packaging motor of bacteriophage ϕ29 is regulated by an arginine finger that extends from one ATPase subunit to the adjacent unit to promote noncovalent dimer formation. Mutation of the arginine finger resulted in the interruption of ATPase oligomerization, ATP binding/hydrolysis, and DNA translocation. Dimer formation reappeared when arginine mutants were mixed with other ATPase subunits that can offer the arginine to promote their interaction ...


Characterization Of The Catalytic Ck2 Subunits With Substitutions At Residues Involved In Inhibitor Binding, Paul Desormeaux Sep 2016

Characterization Of The Catalytic Ck2 Subunits With Substitutions At Residues Involved In Inhibitor Binding, Paul Desormeaux

Electronic Thesis and Dissertation Repository

CK2 is a constitutively active, ubiquitously expressed and pleiotropic serine/threonine protein kinase that is implicated in many cellular functions including tumorigenesis. CK2 has two catalytic subunits, CK2a and CK2a’, that carry out its function in the cell. Previous studies have indicated that inhibitor-refractory mutants have been effective in recovering residual CK2 activity, in the presence of inhibitors, when compared to wild type CK2. Based on these observations, inhibitor-refractory mutants were created for both CK2a and CK2a’ and tested with various concentrations with two CK2-specific inhibitors, CX-4945 and inhibitor VIII. The CK2a triple mutant (V66A/I174A/H160D) was tested in ...


Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros Oct 2015

Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros

Victor R. Ambros

microRNAs function in diverse developmental and physiological processes by regulating target gene expression at the post-transcriptional level. ALG-1 is one of two Caenorhabditis elegans Argonautes (ALG-1 and ALG-2) that together are essential for microRNA biogenesis and function. Here, we report the identification of novel antimorphic (anti) alleles of ALG-1 as suppressors of lin-28(lf) precocious developmental phenotypes. The alg-1(anti) mutations broadly impair the function of many microRNAs and cause dosage-dependent phenotypes that are more severe than the complete loss of ALG-1. ALG-1(anti) mutant proteins are competent for promoting Dicer cleavage of microRNA precursors and for associating with and ...


Micrornas: Genetically Sensitized Worms Reveal New Secrets, Victor Ambros Oct 2015

Micrornas: Genetically Sensitized Worms Reveal New Secrets, Victor Ambros

Victor R. Ambros

Why do many microRNA gene mutants display no evident phenotype? Multiply mutant worms that are selectively impaired in genetic regulatory network activities have been used to uncover previously unknown functions for numerous Caenorhabditis elegans microRNAs.


Translesion Synthesis And Mutations: On The Mutagenic Properties Of The Two Dna Lesions, 8-Oxo-G And Pt-Gg, And The Functions Of Y-Family Dna Polymerases And Rev3l On The Bypass Of Each Of The Dna Lesions In Mammalian Cells, Lizhen Guo Apr 2015

Translesion Synthesis And Mutations: On The Mutagenic Properties Of The Two Dna Lesions, 8-Oxo-G And Pt-Gg, And The Functions Of Y-Family Dna Polymerases And Rev3l On The Bypass Of Each Of The Dna Lesions In Mammalian Cells, Lizhen Guo

Electronic Thesis and Dissertation Repository

I studied the capabilities of the two DNA lesions 8-oxo-guanine and cisplatin intrastrand crosslinked 1,2-d(GpG) or Pt-GG to cause mutations in mammalian cells. Using isogenic cell lines generated from mice with selective gene knockouts of distinct DNA polymerases as models, I deduced the biological functions of the translesion DNA polymerases Pol eta, Pol kappa, Pol iota, Rev1 and Rev3L on bypassing each of the lesions 8-oxo-G and Pt-GG. My study takes advantage of the Next Generation Sequencing (NGS) technology to determine mutagenic effects of the DNA lesions in vivo and effects of translesion DNA polymerases on bypassing the ...


Autonomy And Robustness Of Translocation Through The Nuclear Pore Complex: A Single-Molecule Study, Thomas Dange, David Grunwald, Antje Grunwald, Reiner Peters, Ulrich Kubitscheck Nov 2014

Autonomy And Robustness Of Translocation Through The Nuclear Pore Complex: A Single-Molecule Study, Thomas Dange, David Grunwald, Antje Grunwald, Reiner Peters, Ulrich Kubitscheck

David Grünwald

All molecular traffic between nucleus and cytoplasm occurs via the nuclear pore complex (NPC) within the nuclear envelope. In this study we analyzed the interactions of the nuclear transport receptors kapalpha2, kapbeta1, kapbeta1DeltaN44, and kapbeta2, and the model transport substrate, BSA-NLS, with NPCs to determine binding sites and kinetics using single-molecule microscopy in living cells. Recombinant transport receptors and BSA-NLS were fluorescently labeled by AlexaFluor 488, and microinjected into the cytoplasm of living HeLa cells expressing POM121-GFP as a nuclear pore marker. After bleaching the dominant GFP fluorescence the interactions of the microinjected molecules could be studied using video microscopy ...


Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros Apr 2014

Mutations In Conserved Residues Of The C. Elegans Microrna Argonaute Alg-1 Identify Separable Functions In Alg-1 Mirisc Loading And Target Repression, Anna Y. Zinovyeva, Samir Bouasker, Martin J. Simard, Christopher M. Hammell, Victor R. Ambros

Program in Molecular Medicine Publications

microRNAs function in diverse developmental and physiological processes by regulating target gene expression at the post-transcriptional level. ALG-1 is one of two Caenorhabditis elegans Argonautes (ALG-1 and ALG-2) that together are essential for microRNA biogenesis and function. Here, we report the identification of novel antimorphic (anti) alleles of ALG-1 as suppressors of lin-28(lf) precocious developmental phenotypes. The alg-1(anti) mutations broadly impair the function of many microRNAs and cause dosage-dependent phenotypes that are more severe than the complete loss of ALG-1. ALG-1(anti) mutant proteins are competent for promoting Dicer cleavage of microRNA precursors and for associating with and ...


Mutation And Complementation Of A Cellulose Synthase (Cesa) Gene, Ahmed Y. El-Araby May 2012

Mutation And Complementation Of A Cellulose Synthase (Cesa) Gene, Ahmed Y. El-Araby

Senior Honors Projects

Cellulose is a carbohydrate polymer that is composed of repeating glucose subunits. Being the most abundant organic compound in the biosphere and comprising a large percentage of all plant biomass, cellulose is extremely plentiful and has a significant role in nature. Cellulose is present in plant cell walls, in commercial products such as those made from wood or cotton, and is of interest to the biofuel industry as a potential alternative fuel source. Although indigestible by humans, cellulose is nutritionally valuable, serving as a dietary fiber. Because of its ubiquity and importance in many areas, studying cellulose will prove to ...


Guanosine Diphosphatase Is Required For Protein And Sphingolipid Glycosylation In The Golgi Lumen Of Saccharomyces Cerevisiae, Claudia Abeijon, Ken Yanagisawa, Elisabet Mandon, Alex Hausler, Kelley Moremen, Carlos Hirschberg, Phillips Robbins Feb 2012

Guanosine Diphosphatase Is Required For Protein And Sphingolipid Glycosylation In The Golgi Lumen Of Saccharomyces Cerevisiae, Claudia Abeijon, Ken Yanagisawa, Elisabet Mandon, Alex Hausler, Kelley Moremen, Carlos Hirschberg, Phillips Robbins

Elisabet Mandon

Current models for nucleotide sugar use in the Golgi apparatus predict a critical role for the lumenal nucleoside diphosphatase. After transfer of sugars to endogenous macromolecular acceptors, the enzyme converts nucleoside diphosphates to nucleoside monophosphates which in turn exit the Golgi lumen in a coupled antiporter reaction, allowing entry of additional nucleotide sugar from the cytosol. To test this model, we cloned the gene for the S. cerevisiae guanosine diphosphatase and constructed a null mutation. This mutation should reduce the concentrations of GDP-mannose and GMP and increase the concentration of GDP in the Golgi lumen. The alterations should in turn ...


A Feedback Circuit Involving Let-7-Family Mirnas And Daf-12 Integrates Environmental Signals And Developmental Timing In Caenorhabditis Elegans, Christopher M. Hammell, Xantha Karp, Victor R. Ambros Nov 2009

A Feedback Circuit Involving Let-7-Family Mirnas And Daf-12 Integrates Environmental Signals And Developmental Timing In Caenorhabditis Elegans, Christopher M. Hammell, Xantha Karp, Victor R. Ambros

Victor R. Ambros

Animal development is remarkably robust; cell fates are specified with spatial and temporal precision despite physiological and environmental contingencies. Favorable conditions cause Caenorhabditis elegans to develop rapidly through four larval stages (L1-L4) to the reproductive adult. In unfavorable conditions, L2 larvae can enter the developmentally quiescent, stress-resistant dauer larva stage, enabling them to survive for prolonged periods before completing development. A specific progression of cell division and differentiation events occurs with fidelity during the larval stages, regardless of whether an animal undergoes continuous or dauer-interrupted development. The temporal patterning of developmental events is controlled by the heterochronic genes, whose products ...


Nuclear Export Of 60s Ribosomal Subunits Depends On Xpo1p And Requires A Nuclear Export Sequence-Containing Factor, Nmd3p, That Associates With The Large Subunit Protein Rpl10p, Olivier Gadal, Daniela Strau, Jacques Kessl, Bernard Trumpower Feb 2001

Nuclear Export Of 60s Ribosomal Subunits Depends On Xpo1p And Requires A Nuclear Export Sequence-Containing Factor, Nmd3p, That Associates With The Large Subunit Protein Rpl10p, Olivier Gadal, Daniela Strau, Jacques Kessl, Bernard Trumpower

Open Dartmouth: Peer-reviewed articles by Dartmouth faculty

Nuclear export of ribosomes requires a subset of nucleoporins and the Ran system, but specific transport factors have not been identified. Using a large subunit reporter (Rpl25p-eGFP), we have isolated several temperature-sensitive ribosomal export (rix) mutants. One of these corresponds to the ribosomal protein Rpl10p, which interacts directly with Nmd3p, a conserved and essential protein associated with 60S subunits. We find that thermosensitive nmd3 mutants are impaired in large subunit export. Strikingly, Nmd3p shuttles between the nucleus and cytoplasm and is exported by the nuclear export receptor Xpo1p. Moreover, we show that export of 60S subunits is Xpo1p dependent. We ...