scholarly journals Characterization of a UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase with an unusual lectin domain from the platyhelminth parasite Echinococcus granulosus

2004 ◽  
Vol 382 (2) ◽  
pp. 501-510 ◽  
Author(s):  
Teresa FREIRE ◽  
Cecilia FERNÁNDEZ ◽  
Cora CHALAR ◽  
Rick M. MAIZELS ◽  
Pedro ALZARI ◽  
...  
Keyword(s):  
Echinococcus Granulosus ◽  
Transmembrane Domain ◽  
Functional Characterization ◽  
Maximal Activity ◽  
Structural Features ◽  
Helminth Parasites ◽  
Lectin Domain ◽  
C Terminus ◽  
The One

As part of a general project aimed at elucidating the initiation of mucin-type O-glycosylation in helminth parasites, we have characterized a novel ppGalNAc-T (UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase) from the cestode Echinococcus granulosus (Eg-ppGalNAc-T1). A full-length cDNA was isolated from a library of the tissue-dwelling larval stage of the parasite, and found to code for a 654-amino-acid protein containing all the structural features of ppGalNAc-Ts. Functional characterization of a recombinant protein lacking the transmembrane domain showed maximal activity at 28 °C, in the range 6.5–7.5 pH units and in the presence of Cu2+. In addition, it transferred GalNAc to a broad range of substrate peptides, derived from human mucins and O-glycosylated parasite proteins, including acceptors containing only serine or only threonine residues. Interestingly, the C-terminal region of Eg-ppGalNAc-T1 bears a highly unusual lectin domain, considerably longer than the one from other members of the family, and including only one of the three ricin B repeats generally present in ppGalNAc-Ts. Furthermore, a search for conserved domains within the protein C-terminus identified a fragment showing similarity to a recently defined domain, specialized in the binding of organic phosphates (CYTH). The role of the lectin domain in the determination of the substrate specificity of these enzymes suggests that Eg-ppGalNAc-T1 would be involved in the glycosylation of a special type of substrate. Analysis of the tissue distribution by in situ hybridization and immunohistochemistry revealed that this transferase is expressed in the hydatid cyst wall and the subtegumental region of larval worms. Therefore it could participate in the biosynthesis of O-glycosylated parasite proteins exposed at the interface between E. granulosus and its hosts.

FUNCTIONAL CHARACTERIZATION OF AN LCCL–LECTIN DOMAIN CONTAINING PROTEIN FAMILY IN PLASMODIUM BERGHEI

2004 ◽  
Vol 90 (5) ◽  
pp. 1062-1071 ◽  
Author(s):  
Holly E. Trueman ◽  
J. Dale Raine ◽  
Laurence Florens ◽  
Johannes T. Dessens ◽  
Jacqui Mendoza ◽  
...  
Keyword(s):  
Plasmodium Berghei ◽  
Functional Characterization ◽  
Protein Family ◽  
Lectin Domain

Evi-2, a common integration site involved in murine myeloid leukemogenesis

1990 ◽  
Vol 10 (9) ◽  
pp. 4658-4666
Author(s):  
A M Buchberg ◽  
H G Bedigian ◽  
N A Jenkins ◽  
N G Copeland
Keyword(s):  
Leucine Zipper ◽  
Transmembrane Domain ◽  
Integration Site ◽  
Transmembrane Protein ◽  
Structural Features ◽  
Viral Integration ◽  
Integration Sites ◽  
Leukemia Viruses ◽  
Common Integration Site

BXH-2 mice have the highest incidence of spontaneous retrovirally induced myeloid leukemia of any known inbred strain and, as such, represent a valuable model system for identifying cellular proto-oncogenes involved in myeloid disease. Chronic murine leukemia viruses often induce disease by insertional activation or mutation of cellular proto-oncogenes. These loci are identified as common viral integration sites in tumor DNAs. Here we report on the characterization of a novel common viral integration site in BXH-2 myeloid leukemias, designated Evi-2. Within the cluster of viral integration sites that define Evi-2, we identified a gene that has the potential for encoding a novel protein of 223 amino acids. This putative proto-oncogene possesses all of the structural features of a transmembrane protein. Within the transmembrane domain is a "leucine zipper," suggesting that Evi-2 is involved in either homopolymer or heteropolymer formation, which may play an important role in the normal functioning of Evi-2. Interestingly, the human homolog of Evi-2 has recently been shown to be tightly linked to the von Recklinghausen neurofibromatosis locus, suggesting a role for Evi-2 in human disease as well.

scholarly journals Structural and functional characterization of the pore-forming domain of pinholin S2168

2020 ◽  
Vol 117 (47) ◽  
pp. 29637-29646
Author(s):  
Lena M. E. Steger ◽  
Annika Kohlmeyer ◽  
Parvesh Wadhwani ◽  
Jochen Bürck ◽  
Erik Strandberg ◽  
...  
Keyword(s):  
Experimental Data ◽  
Order Parameter ◽  
Transmembrane Domain ◽  
Functional Characterization ◽  
Azimuthal Angle ◽  
Structural Models ◽  
Lytic Cycle ◽  
Helical Conformation ◽  
Rotational Orientation

Pinholin S2168 triggers the lytic cycle of bacteriophage φ21 in infectedEscherichia coli. Activated transmembrane dimers oligomerize into small holes and uncouple the proton gradient. Transmembrane domain 1 (TMD1) regulates this activity, while TMD2 is postulated to form the actual “pinholes.” Focusing on the TMD2 fragment, we used synchrotron radiation-based circular dichroism to confirm its α-helical conformation and transmembrane alignment. Solid-state15N-NMR in oriented DMPC bilayers yielded a helix tilt angle of τ = 14°, a high order parameter (Smol= 0.9), and revealed the azimuthal angle. The resulting rotational orientation places an extended glycine zipper motif (G40xxxS44xxxG48) together with a patch of H-bonding residues (T51, T54, N55) sideways along TMD2, available for helix–helix interactions. Using fluorescence vesicle leakage assays, we demonstrate that TMD2 forms stable holes with an estimated diameter of 2 nm, as long as the glycine zipper motif remains intact. Based on our experimental data, we suggest structural models for the oligomeric pinhole (right-handed heptameric TMD2 bundle), for the active dimer (right-handed Gly-zipped TMD2/TMD2 dimer), and for the full-length pinholin protein before being triggered (Gly-zipped TMD2/TMD1-TMD1/TMD2 dimer in a line).

scholarly journals Functional Characterization of the Interaction of Ste50p with Ste11p MAPKKK inSaccharomyces cerevisiae

1999 ◽  
Vol 10 (7) ◽  
pp. 2425-2440 ◽  
Author(s):  
Cunle Wu ◽  
Ekkehard Leberer ◽  
David Y. Thomas ◽  
Malcolm Whiteway
Keyword(s):  
Protein Kinase ◽  
Functional Characterization ◽  
Hog Pathway ◽  
C Terminus ◽  
Extracellular Signal ◽  
Osmotic Stress Response ◽  
N Terminus

The Saccharomyces cerevisiae Ste11p protein kinase is a homologue of mammalian MAPK/extracellular signal-regulated protein kinase kinase kinases (MAPKKKs or MEKKs) as well as theSchizosaccharomyces pombe Byr2p kinase. Ste11p functions in several signaling pathways, including those for mating pheromone response and osmotic stress response. The Ste11p kinase has an N-terminal domain that interacts with other signaling molecules to regulate Ste11p function and direct its activity in these pathways. One of the Ste11p regulators is Ste50p, and Ste11p and Ste50p associate through their respective N-terminal domains. This interaction relieves a negative activity of the Ste11p N terminus, and removal of this negative function is required for Ste11p function in the high-osmolarity glycerol (HOG) pathway. The Ste50p/Ste11p interaction is also important (but not essential) for Ste11p function in the mating pathway; in this pathway binding of the Ste11p N terminus with both Ste50p and Ste5p is required, with the Ste5p association playing the major role in Ste11p function. In vitro, Ste50p disrupts an association between the catalytic C terminus and the regulatory N terminus of Ste11p. In addition, Ste50p appears to modulate Ste11p autophosphorylation and is itself a substrate of the Ste11p kinase. Therefore, both in vivo and in vitro data support a role for Ste50p in the regulation of Ste11p activity.

scholarly journals Highly diverged novel subunit composition of apicomplexan F-type ATP synthase identified from Toxoplasma gondii

2018 ◽  
Author(s):  
Rahul Salunke ◽  
Tobias Mourier ◽  
Manidipa Banerjee ◽  
Arnab Pain ◽  
Dhanasekaran Shanmugam
Keyword(s):  
Toxoplasma Gondii ◽  
Atp Synthase ◽  
Functional Characterization ◽  
Structural Features ◽  
Subunit Composition ◽  
Mass Spectrometry Analysis ◽  
Spectrometry Analysis ◽  
Apicomplexan Parasites ◽  
Fundamental Understanding

AbstractThe mitochondrial F-type ATP synthase, a multi-subunit nanomotor, is critical for maintaining cellular ATP levels. In Toxoplasma gondii and other apicomplexan parasites, many subunit components, necessary for proper assembly and functioning of this enzyme, appear to be missing. Here, we report the identification of 20 novel subunits of T. gondii F-type ATP synthase from mass spectrometry analysis of partially purified monomeric (~600 kDa) and dimeric (>1 MDa) forms of the enzyme. Despite extreme sequence diversification, key FO subunits, a, b and d, can be identified from conserved structural features. Orthologs for these proteins are restricted to apicomplexan, chromerid and dinoflagellate species. Interestingly, their absence in ciliates indicates a major diversion, with respect to subunit composition of this enzyme, within the alveolate clade. Discovery of these highly diversified novel components of the apicomplexan F-type ATP synthase complex could facilitate the development of novel anti-parasitic agents. Structural and functional characterization of this unusual enzyme complex will advance our fundamental understanding of energy metabolism in apicomplexan species.

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