Biophysical characterization of Entamoeba histolytica phosphoserine aminotransferase (EhPSAT): role of cofactor and domains in stability and subunit assembly

2010 ◽  
Vol 40 (5) ◽  
pp. 599-610 ◽  
Author(s):  
Vibhor Mishra ◽  
Vahab Ali ◽  
Tomoyoshi Nozaki ◽  
Vinod Bhakuni
Keyword(s):  
Entamoeba Histolytica ◽  
Biophysical Characterization ◽  
Subunit Assembly ◽  
Phosphoserine Aminotransferase

scholarly journals Functional Characterization of Spliceosomal Introns and Identification of U2, U4, and U5 snRNAs in the Deep-Branching Eukaryote Entamoeba histolytica

2007 ◽  
Vol 6 (6) ◽  
pp. 940-948 ◽  
Author(s):  
Carrie A. Davis ◽  
Michael P. S. Brown ◽  
Upinder Singh
Keyword(s):  
Entamoeba Histolytica ◽  
Splice Site ◽  
Expressed Sequence Tag ◽  
Functional Characterization ◽  
Molecular Evidence ◽  
Spliceosomal Introns ◽  
Accurate Expression ◽  
Eukaryotic Organisms

ABSTRACT Pre-mRNA splicing is essential to ensure accurate expression of many genes in eukaryotic organisms. In Entamoeba histolytica, a deep-branching eukaryote, approximately 30% of the annotated genes are predicted to contain introns; however, the accuracy of these predictions has not been tested. In this study, we mined an expressed sequence tag (EST) library representing 7% of amoebic genes and found evidence supporting splicing of 60% of the testable intron predictions, the majority of which contain a GUUUGU 5′ splice site and a UAG 3′ splice site. Additionally, we identified several splice site misannotations, evidence for the existence of 30 novel introns in previously annotated genes, and identified novel genes through uncovering their spliced ESTs. Finally, we provided molecular evidence for the E. histolytica U2, U4, and U5 snRNAs. These data lay the foundation for further dissection of the role of RNA processing in E. histolytica gene expression.

scholarly journals Dissecting the role of glutamine in seeding peptide aggregation

2020 ◽  
Author(s):  
Exequiel E. Barrera ◽  
Francesco Zonta ◽  
Sergio Pantano
Keyword(s):  
Molecular Weight ◽  
Structural Heterogeneity ◽  
Low Molecular Weight ◽  
Biophysical Characterization ◽  
Aggregation Propensity ◽  
Toxic Species ◽  
Dynamical Nature ◽  
Spatio Temporal

ABSTRACTPoly glutamine and glutamine-rich peptides play a central role in a plethora of pathological aggregation events. However, biophysical characterization of soluble oligomers —the most toxic species involved in these processes— remains elusive due to their structural heterogeneity and dynamical nature. Here, we exploit the high spatio-temporal resolution of simulations as a computational microscope to characterize the aggregation propensity and morphology of a series of polyglutamine and glutamine-rich peptides. Comparative analysis of ab-initio aggregation pinpointed a double role for glutamines. In the first phase, glutamines mediate seeding by pairing monomeric peptides, which serve as primers for higher-order nucleation. According to the glutamine content, these low molecular-weight oligomers may then proceed to create larger aggregates. Once within the aggregates, buried glutamines continue to play a role in their maturation by optimizing solvent-protected hydrogen bonds networks.TOC / Abstract Figure

Crystal structures of a β-trefoil lectin from Entamoeba histolytica in monomeric and a novel disulfide bond-mediated dimeric forms

Glycobiology ◽  
2020 ◽  
Vol 30 (7) ◽  
pp. 474-488 ◽  
Author(s):  
Farha Khan ◽  
Devanshu Kurre ◽  
K Suguna
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Entamoeba Histolytica ◽  
Disulfide Bond ◽  
Structural Basis ◽  
Free Form ◽  
Biophysical Characterization ◽  
Biophysical Studies ◽  
First Time

Abstract β-Trefoil lectins are galactose/N-acetyl galactosamine specific lectins, which are widely distributed across all kingdoms of life and are known to perform several important functions. However, there is no report available on the characterization of these lectins from protozoans. We have performed structural and biophysical studies on a β-trefoil lectin from Entamoeba histolytica (EntTref), which exists as a mixture of monomers and dimers in solution. Further, we have determined the affinities of EntTref for rhamnose, galactose and different galactose-linked sugars. We obtained the crystal structure of EntTref in a sugar-free form (EntTref_apo) and a rhamnose-bound form (EntTref_rham). A novel Cys residue-mediated dimerization was revealed in the crystal structure of EntTref_apo while the structure of EntTref_rham provided the structural basis for the recognition of rhamnose by a β-trefoil lectin for the first time. To the best of our knowledge, this is the only report of the structural, functional and biophysical characterization of a β-trefoil lectin from a protozoan source and the first report of Cys-mediated dimerization in this class of lectins.

Biochemical and biophysical characterization of the smallest pyruvate kinase from Entamoeba histolytica

2020 ◽  
Vol 1868 (1) ◽  
pp. 140296
Author(s):  
Poonam Kumari ◽  
Danish Idrees ◽  
Pragyan Parimita Rath ◽  
Ramachandran Vijayan ◽  
Samudrala Gourinath
Keyword(s):  
Pyruvate Kinase ◽  
Entamoeba Histolytica ◽  
Biophysical Characterization

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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