Showing 221 - 230 of 257 Items
Protein arginine methylation in Candida albicans: Role in nuclear transport
Date: 2007-07-01
Creator: Anne E. McBride, Cecilia Zurita-Lopez, Anthony Regis, Emily Blum, Ana, Conboy, Shannon Elf, Steven Clarke
Access: Open access
- Protein arginine methylation plays a key role in numerous eukaryotic processes, such as protein transport and signal transduction. In Candida albicans, two candidate protein arginine methyltransferases (PRMTs) have been identified from the genome sequencing project. Based on sequence comparison, C. albicans candidate PRMTs display similarity to Saccharomyces cerevisiae Hmt1 and Rmt2. Here we demonstrate functional homology of Hmt1 between C. albicans and S. cerevisiae: CaHmt1 supports growth of S. cerevisiae strains that require Hmt1, and CaHmt1 methylates Npl3, a major Hmt1 substrate, in S. cerevisiae. In C. albicans strains lacking CaHmt1, asymmetric dimethylarginine and ω-monomethylarginine levels are significantly decreased, indicating that Hmt1 is the major C. albicans type I PRMT1. Given the known effects of type I PRMTs on nuclear transport of RNA-binding proteins, we tested whether Hmt1 affects nuclear transport of a putative Npl3 ortholog in C. albicans. CaNpl3 allows partial growth of S. cerevisiae npl3Δ strains, but its arginine-glycine-rich C terminus can fully substitute for that of ScNpl3 and also directs methylation-sensitive association with ScNpl3. Expression of green fluorescent protein-tagged CaNpl3 proteins in C. albicans strains with and without CaHmt1 provides evidence for CaHmt1 facilitating export of CaNpl3 in this fungus. We have also identified the C. albicans Rmt2, a type IV fungus- and plant-specific PRMT, by amino acid analysis of an rmt2Δ/rmt2Δ strain, as well as biochemical evidence for additional cryptic PRMTs. Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Human protein Sam68 relocalization and interaction with poliovirus RNA polymerase in infected cells
Date: 1996-03-19
Creator: A. E. Mcbride, A. Schlegel, K. Kirkegaard
Access: Open access
- A HeLa cDNA expression library was screened for human polypeptides that interacted with the poliovirus RNA-dependent RNA polymerase, 3D, using the two-hybrid system in the yeast Saccharomyces cerevisiae. Sam68 (Src- associated in mitosis, 68 kDa) emerged as the human cDNA that, when fused to a transcriptional activation domain, gave the strongest 3D interaction signal with a LexA-3D hybrid protein. 3D polymerase and Sam68 coimmunoprecipitated from infected human cell lysates with antibodies that recognized either protein. Upon poliovirus infection. Sam68 relocalized from the nucleus to the cytoplasm, where poliovirus replication occurs. Sam68 was isolated from infected cell lysates with an antibody that recognizes poliovirus protein 2C, suggesting that it is found on poliovirus-induced membranes upon which viral RNA synthesis occurs. These data, in combination with the known RNA- and protein-binding properties of Sam68, make Sam68 a strong candidate for a host protein with a functional role in poliovirus replication.
Xanthophyll cycle activity in two prominent arctic shrub species
Date: 2017-01-01
Creator: T.S. Magney, B.A. Logan, J.S. Reblin, N.T. Boelman, J.U.H., Eitel, H.E. Greaves, K.L. Griffin, C.M. Prager, L.A. Vierling
Access: Open access
Live imaging and biophysical modeling support a button-based mechanism of somatic homolog pairing in Drosophila
Date: 2021-06-01
Creator: Myron Child, Jack R. Bateman, Amir Jahangiri, Armando Reimer, Nicholas C., Lammers, Nica Sabouni, Diego Villamarin, Grace C. McKenzie-Smith, Justine E. Johnson, Daniel Jost, Hernan G. Garcia
Access: Open access
- 3D eukaryotic genome organization provides the structural basis for gene regulation. In Drosophila melanogaster, genome folding is characterized by somatic homolog pairing, where homologous chromosomes are intimately paired from end to end; however, how homologs identify one another and pair has remained mysterious. Recently, this process has been proposed to be driven by specifically interacting “buttons” encoded along chromosomes. Here, we turned this hypothesis into a quantitative biophysical model to demonstrate that a button-based mechanism can lead to chromosome-wide pairing. We tested our model using live-imaging measurements of chromosomal loci tagged with the MS2 and PP7 nascent RNA labeling systems. We show solid agreement between model predictions and experiments in the pairing dynamics of individual homologous loci. Our results strongly support a button-based mechanism of somatic homolog pairing in Drosophila and provide a theoretical framework for revealing the molecular identity and regulation of buttons.
Positive Effects of Nonnative Invasive Phragmites australis on Larval Bullfrogs
Date: 2012-08-30
Creator: Mary Rogalski
Access: Open access
islet reveals segmentation in the amphioxus hindbrain homolog
Date: 2000-04-01
Creator: William R. Jackman, James A. Langeland, Charles B. Kimmel
Access: Open access
- The vertebrate embryonic hindbrain is segmented into rhombomeres. Gene expression studies suggest that amphioxus, the closest invertebrate relative of vertebrates, has a hindbrain homolog. However, this region is not overtly segmented in amphioxus, raising the question of how hindbrain segmentation arose in chordate evolution. Vertebrate hindbrain segmentation includes the patterning of cranial motor neurons, which can be identified by their expression of the LIM-homeodomain transcription factor islet1. To learn if the amphioxus hindbrain homolog is cryptically segmented, we cloned an amphioxus gene closely related to islet1, which we named simply islet. We report that amphioxus islet expression includes a domain of segmentally arranged cells in the ventral hindbrain homolog. We hypothesize that these cells are developing motor neurons and reveal a form of hindbrain segmentation in amphioxus. Hence, vertebrate rhombomeres may derive from a cryptically segmented brain present in the amphioxus/vertebrate ancestor. Other islet expression domains provide evidence for amphioxus homologs of the pineal gland, adenohypophysis, and endocrine pancreas. Surprisingly, homologs of vertebrate islet1-expressing spinal motor neurons and Rohon-Beard sensory neurons appear to be absent. (C) 2000 Academic Press.
Rapid oligo-galacturonide induced changes in protein phosphorylation in arabidopsis
Date: 2016-04-01
Creator: Bruce D. Kohorn, Divya Hoon, Benjamin B. Minkoff, Michael R. Sussman, Susan L., Kohorn
Access: Open access
- The wall-associated kinases (WAKs)1 are receptor protein kinases that bind to long polymers of cross-linked pectin in the cell wall. These plasma-membrane-associated protein kinases also bind soluble pectin fragments called oligo-galacturonides (OGs) released from the wall after pathogen attack and damage. WAKs are required for cell expansion during development but bind water soluble OGs generated from walls with a higher affinity than the wall-associated polysaccharides. OGs activate a WAKdependent, distinct stress-like response pathway to help plants resist pathogen attack. In this report, a quantitative mass-spectrometric-based phosphoproteomic analysis was used to identify Arabidopsis cellular events rapidly induced by OGs in planta. Using N14/ N15 isotopic in vivo metabolic labeling, we screened 1,000 phosphoproteins for rapid OG-induced changes and found 50 proteins with increased phosphorylation, while there were none that decreased significantly. Seven of the phosphosites within these proteins overlap with those altered by another signaling molecule plants use to indicate the presence of pathogens (the bacterial "elicitor" peptide Flg22), indicating distinct but overlapping pathways activated by these two types of chemicals. Genetic analysis of genes encoding 10 OG-specific and two Flg22/OG-induced phosphoproteins reveals that null mutations in eight proteins compromise the OG response. These phosphorylated proteins with genetic evidence supporting their role in the OG response include two cytoplasmic kinases, two membrane-associated scaffold proteins, a phospholipase C, a CDPK, an unknown cadmium response protein, and a motor protein. Null mutants in two proteins, the putative scaffold protein REM1.3, and a cytoplasmic receptor like kinase ROG2, enhance and suppress, respectively, a dominant WAK allele. Altogether, the results of these chemical and genetic experiments reveal the identity of several phosphorylated proteins involved in the kinase/ phosphatase-mediated signaling pathway initiated by cell wall changes.
Cell wall-associated kinases and pectin perception
Date: 2016-01-01
Creator: Bruce D. Kohorn
Access: Open access
- The pectin matrix of the angiosperm cell wall is regulated in both synthesis and modification and greatly influences the direction and extent of cell growth. Pathogens, herbivory and mechanical stresses all influence this pectin matrix and consequently plant form and function. The cell wall-associated kinases (WAKs) bind to pectin and regulate cell expansion or stress responses depending upon the state of the pectin. This review explores the WAKs in the context of cell wall biology and signal transduction pathways.
Transvection-based gene regulation in Drosophila is a complex and plastic trait
Date: 2014-01-01
Creator: Xinyang Bing, Teresa Z. Rzezniczak, Jack R. Bateman, Thomas J.S. Merritt
Access: Open access
- Transvection, a chromosome pairing-dependent form of trans-based gene regulation, is potentially widespread in the Drosophila melanogaster genome and varies across cell types and within tissues in D. melanogaster, characteristics of a complex trait. Here, we demonstrate that the trans-interactions at the Malic enzyme (Men) locus are, in fact, transvection as classically defined and are plastic with respect to both genetic background and environment. Using chromosomal inversions, we show that trans-interactions at the Men locus are eliminated by changes in chromosomal architecture that presumably disrupt somatic pairing. We further show that the magnitude of transvection at the Men locus is modified by both genetic background and environment (temperature), demonstrating that transvection is a plastic phenotype. Our results suggest that transvection effects in D. melanogaster are shaped by a dynamic interplay between environment and genetic background. Interestingly, we find that cis-based regulation of the Men gene is more robust to genetic background and environment than trans-based. Finally, we begin to uncover the nonlocal factors that may contribute to variation in transvection overall, implicating Abd-B in the regulation of Men in cis and in trans in an allele-specific and tissue-specific manner, driven by differences in expression of the two genes across genetic backgrounds and environmental conditions.
Taming the giant within
Date: 2019-01-01
Creator: Jack R. Bateman, David J. Anderson
Access: Open access