Halophilic class I aldolase and glyceraldehyde-3-phosphate dehydrogenase: Some salt-dependent structural features

Biochemistry ◽  
1993 ◽  
Vol 32 (3) ◽  
pp. 791-798 ◽  
Author(s):  
Gomathi Krishnan ◽  
Wijaya Altekar
Keyword(s):  
Structural Features ◽  
Class I ◽  
Class I Aldolase

scholarly journals Variations in MHC class I antigen presentation and immunopeptidome selection pathways

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 1177
Author(s):  
Anita J. Zaitouna ◽  
Amanpreet Kaur ◽  
Malini Raghavan
Keyword(s):  
Cell Surface ◽  
Antigen Presentation ◽  
Surface Expression ◽  
Structural Features ◽  
Class I ◽  
Cell Surface Expression ◽  
Immune Recognition ◽  
Antigen Receptors ◽  
Class I Mhc ◽  
Mhc I

Major histocompatibility class I (MHC-I) proteins mediate immunosurveillance against pathogens and cancers by presenting antigenic or mutated peptides to antigen receptors of CD8+ T cells and by engaging receptors of natural killer (NK) cells. In humans, MHC-I molecules are highly polymorphic. MHC-I variations permit the display of thousands of distinct peptides at the cell surface. Recent mass spectrometric studies have revealed unique and shared characteristics of the peptidomes of individual MHC-I variants. The cell surface expression of MHC-I–peptide complexes requires the functions of many intracellular assembly factors, including the transporter associated with antigen presentation (TAP), tapasin, calreticulin, ERp57, TAP-binding protein related (TAPBPR), endoplasmic reticulum aminopeptidases (ERAPs), and the proteasomes. Recent studies provide important insights into the structural features of these factors that govern MHC-I assembly as well as the mechanisms underlying peptide exchange. Conformational sensing of MHC-I molecules mediates the quality control of intracellular MHC-I assembly and contributes to immune recognition by CD8 at the cell surface. Recent studies also show that several MHC-I variants can follow unconventional assembly routes to the cell surface, conferring selective immune advantages that can be exploited for immunotherapy.

Multiple recruitment of class-I aldolase to chloroplasts and eubacterial origin of eukaryotic class-II aldolases revealed by cDNAs from Euglena gracilis

1997 ◽  
Vol 31 (5) ◽  
pp. 430-438 ◽  
Author(s):  
Marlies Plaumann ◽  
Birgit Pelzer-Reith ◽  
William F. Martin ◽  
C. Schnarrenberger
Keyword(s):  
Euglena Gracilis ◽  
Class Ii ◽  
Class I ◽  
Class I Aldolase

scholarly journals Structural features for peptides binding the class I molecules

2001 ◽  
Vol 3 (S1) ◽  
Author(s):  
I McKenzie ◽  
V Apostolopoulos ◽  
Y Mu ◽  
IA Wilson
Keyword(s):  
Structural Features ◽  
Class I

scholarly journals Crystal structure of transaldolase B from Escherichia coli suggests a circular permutation of the α/β barrel within the class I aldolase family

Structure ◽  
1996 ◽  
Vol 4 (6) ◽  
pp. 715-724 ◽  
Author(s):  
Jia Jia ◽  
Weijun Huang ◽  
Ulrich Schö rken ◽  
Hermann Sahm ◽  
Georg A Sprenger ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Circular Permutation ◽  
Class I ◽  
Class I Aldolase

scholarly journals H-2Kd-restricted antigenic peptides share a simple binding motif.

1991 ◽  
Vol 174 (3) ◽  
pp. 603-612 ◽  
Author(s):  
P Romero ◽  
G Corradin ◽  
I F Luescher ◽  
J L Maryanski
Keyword(s):  
Amino Acid ◽  
Mhc Class I ◽  
Specific Binding ◽  
Structural Features ◽  
Class I ◽  
Binding Motif ◽  
Antigenic Peptides ◽  
Amino Acid Residues ◽  
Antigenic Activity ◽  
Mhc Class I Molecule

We have defined structural features that are apparently important for the binding of four different, unrelated antigenic epitopes to the same major histocompatibility complex (MHC) class I molecule, H-2Kd. The four epitopes are recognized in the form of synthetic peptides by cytotoxic T lymphocytes of the appropriate specificity. By analysis of the relative potency of truncated peptides, we demonstrated that for each of the four epitopes, optimal antigenic activity was present in a peptide of 9 or 10 amino acid residues. A comparison of the relative competitor activity of the different-length peptides in a functional competition assay, as well as in a direct binding assay based on photoaffinity labeling of the Kd molecule, indicated that the enhanced potency of the peptides upon reduction in length was most likely due to a higher affinity of the shorter peptides for the Kd molecule. A remarkably simple motif that appears to be important for the specific binding of Kd-restricted peptides was identified by the analysis of peptides containing amino acid substitutions or deletions. The motif consists of two elements, a Tyr in the second position relative to the NH2 terminus and a hydrophobic residue with a large aliphatic side chain (Leu, Ile, or Val) at the COOH-terminal end of the optimal 9- or 10-mer peptides. We demonstrated that a simple peptide analogue (AYP6L) that incorporates the motif can effectively and specifically interact with the Kd molecule. Moreover, all of the additional Kd-restricted epitopes defined thus far in the literature contain the motif, and it may thus be useful for the prediction of new epitopes recognized by T cells in the context of this MHC class I molecule.

scholarly journals Potential Immunocompetence of Proteolytic Fragments Produced by Proteasomes before Evolution of the Vertebrate Immune System

1997 ◽  
Vol 186 (2) ◽  
pp. 209-220 ◽  
Author(s):  
Gabriele Niedermann ◽  
Rudolf Grimm ◽  
Elke Geier ◽  
Martina Maurer ◽  
Claudio Realini ◽  
...  
Keyword(s):  
Immune System ◽  
Mhc Class I ◽  
Structural Features ◽  
Interferon Γ ◽  
Class I ◽  
Direct Products ◽  
Vertebrate Immune System ◽  
Mhc Class I Molecules

To generate peptides for presentation by major histocompatibility complex (MHC) class I molecules to T lymphocytes, the immune system of vertebrates has recruited the proteasomes, phylogenetically ancient multicatalytic high molecular weight endoproteases. We have previously shown that many of the proteolytic fragments generated by vertebrate proteasomes have structural features in common with peptides eluted from MHC class I molecules, suggesting that many MHC class I ligands are direct products of proteasomal proteolysis. Here, we report that the processing of polypeptides by proteasomes is conserved in evolution, not only among vertebrate species, but including invertebrate eukaryotes such as insects and yeast. Unexpectedly, we found that several high copy ligands of MHC class I molecules, in particular, self-ligands, are major products in digests of source polypeptides by invertebrate proteasomes. Moreover, many major dual cleavage peptides produced by invertebrate proteasomes have the length and the NH2 and COOH termini preferred by MHC class I. Thus, the ability of proteasomes to generate potentially immunocompetent peptides evolved well before the vertebrate immune system. We demonstrate with polypeptide substrates that interferon γ induction in vivo or addition of recombinant proteasome activator 28α in vitro alters proteasomal proteolysis in such a way that the generation of peptides with the structural features of MHC class I ligands is optimized. However, these changes are quantitative and do not confer qualitatively novel characteristics to proteasomal proteolysis. The data suggest that proteasomes may have influenced the evolution of MHC class I molecules.

Substrate Selectivity and Biochemical Properties of 4-Hydroxy-2-Keto-Pentanoic Acid Aldolase from Escherichia coli

1998 ◽  
Vol 64 (10) ◽  
pp. 4093-4094 ◽  
Author(s):  
John R. Pollard ◽  
Delphine Rialland ◽  
Timothy D. H. Bugg
Keyword(s):  
Escherichia Coli ◽  
Pyruvic Acid ◽  
Biochemical Properties ◽  
Class I ◽  
Substrate Selectivity ◽  
Pentanoic Acid ◽  
Phenylpyruvic Acid ◽  
Class I Aldolase

ABSTRACT 4-Hydroxy-2-keto-pentanoic acid aldolase from Escherichia coli was identified as a class I aldolase. The enzyme was found to be highly selective for the acetaldehyde acceptor but would accept α-ketobutyric acid or phenylpyruvic acid in place of the pyruvic acid carbonyl donor.

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