scholarly journals Transmembrane features governing Fc receptor CD16A assembly with CD16A signaling adaptor molecules

2017 ◽  
Vol 114 (28) ◽  
pp. E5645-E5654 ◽  
Author(s):  
Alfonso Blázquez-Moreno ◽  
Soohyung Park ◽  
Wonpil Im ◽  
Melissa J. Call ◽  
Matthew E. Call ◽  
...  
Keyword(s):  
Surface Expression ◽  
Site Directed Mutagenesis ◽  
Solution Nmr ◽  
Receptor Complex ◽  
Hydrogen Bond Network ◽  
The Core ◽  
High Sequence Homology ◽  
Bond Network ◽  
Tm Domain ◽  
Signaling Modules

Many activating immunoreceptors associate with signaling adaptor molecules like FcεR1γ or CD247. FcεR1γ and CD247 share high sequence homology and form disulphide-linked homodimers that contain a pair of acidic aspartic acid residues in their transmembrane (TM) domains that mediate assembly, via interaction with an arginine residue at a similar register to these aspartic acids, with the activating immunoreceptors. However, this model cannot hold true for receptors like CD16A, whose TM domains do not contain basic residues. We have carried out an extensive site-directed mutagenesis analysis of the CD16A receptor complex and now report that the association of receptor with the signaling adaptor depends on a network of polar and aromatic residues along the length of the TM domain. Molecular modeling indicates that CD16A TM residues F202, D205, and T206 form the core of the membrane-embedded trimeric interface by establishing highly favorable contacts to the signaling modules through rearrangement of a hydrogen bond network previously identified in the CD247 TM dimer solution NMR structure. Strikingly, the amino acid D205 also regulates the turnover and surface expression of CD16A in the absence of FcεR1γ or CD247. Modeling studies indicate that similar features underlie the association of other activating immune receptors, including CD64 and FcεR1α, with signaling adaptor molecules, and we confirm experimentally that equivalent F, D, and T residues in the TM domain of FcεR1α markedly influence the biology of this receptor and its association with FcεR1γ.

scholarly journals Structure-Based Site-Directed Mutagenesis of the UDP-MurNAc-Pentapeptide-Binding Cavity of the FemX Alanyl Transferase from Weissella viridescens

2005 ◽  
Vol 187 (11) ◽  
pp. 3833-3838 ◽  
Author(s):  
Antoine P. Maillard ◽  
Sabrina Biarrotte-Sorin ◽  
Régis Villet ◽  
Stéphane Mesnage ◽  
Ahmed Bouhss ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Transferase Activity ◽  
Hydrogen Bond Network ◽  
Gram Positive Bacteria ◽  
Binding Cavity ◽  
Bond Network ◽  
Phosphate Groups

ABSTRACT Weissella viridescens FemX (FemXWv) belongs to the Fem family of nonribosomal peptidyl transferases that use aminoacyl-tRNA as the amino acid donor to synthesize the peptide cross-bridge found in the peptidoglycan of many species of pathogenic gram-positive bacteria. We have recently solved the crystal structure of FemXWv in complex with the peptidoglycan precursor UDP-MurNAc-pentapeptide and report here the site-directed mutagenesis of nine residues located in the binding cavity for this substrate. Two substitutions, Lys36Met and Arg211Met, depressed FemXWv transferase activity below detectable levels without affecting protein folding. Analogues of UDP-MurNAc-pentapeptide lacking the phosphate groups or the C-terminal d-alanyl residues were not substrates of the enzyme. These results indicate that Lys36 and Arg211 participate in a complex hydrogen bond network that connects the C-terminal d-Ala residues to the phosphate groups of UDP-MurNAc-pentapeptide and constrains the substrate in a conformation that is essential for transferase activity.

scholarly journals Regulation of murine MHC class II molecule expression. Identification of A beta residues responsible for allele-specific cell surface expression.

1988 ◽  
Vol 168 (3) ◽  
pp. 823-837 ◽  
Author(s):  
J M Buerstedde ◽  
L R Pease ◽  
A E Nilson ◽  
M P Bell ◽  
C Chase ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class Ii ◽  
Surface Expression ◽  
Class Ii ◽  
Site Directed Mutagenesis ◽  
Cell Surface Expression ◽  
Specific Cell ◽  
Specific Expression ◽  
The Core ◽  
Allele Specific

A panel of mutant class II genes have been constructed using site-directed mutagenesis and DNA-mediated gene transfer. Using this technique, Ak beta polypeptides have been altered by substituting one or more Ad beta-specific residues at polymorphic positions in the beta 1 domain. Transfection of M12.C3 B lymphoma cells with most mutant Ak beta* genes results in the expression of Ak beta* Ad alpha molecules on the cell surface. However, the substitution of a single d allele residue at position 78 or 86 in the Ak beta polypeptide results in either the complete absence or very low levels, respectively, of cell surface expression of the Ak beta* Ad alpha molecule, but does not alter Ak beta* Ak alpha expression. The T.86 Ak beta* Ad alpha is expressed primarily in an intracellular compartment while the T.78 Ak beta* molecule does not appear to be produced. The core-glycosylated T.78 Ak beta* polypeptide does, however, form a complex intracellularly with the core-glycosylated Ii polypeptide. Substitution of the combination of d allele residues at Ak beta polymorphic positions 9, 12, 13, 14, and 17 results in the absence of Ak beta* Ak alpha cell surface expression but does not alter the expression of this mutant Ak beta* polypeptide with the Ad alpha polypeptide. These allele-specific expression mutants demonstrate that substitution at certain beta 1 domain positions may result in the alteration of Ia cell surface expression and that the transport of Ia molecules from the Golgi apparatus to the cell surface may be regulated by signals that are determined by the interaction of polymorphic residues in both the alpha and beta polypeptides.

scholarly journals Interleukin-2 druggability is modulated by global conformational transitions controlled by a helical capping switch

2019 ◽  
Author(s):  
Viviane S. De Paula ◽  
Kevin M. Jude ◽  
Santrupti Nerli ◽  
Caleb R. Glassman ◽  
K. Christopher Garcia ◽  
...  
Keyword(s):  
Immune Cell ◽  
Interleukin 2 ◽  
Hydrogen Bond Network ◽  
Combination Therapies ◽  
The Core ◽  
Cell Compartments ◽  
Molecule Inhibitor ◽  
Conformational Plasticity ◽  
Bond Network ◽  
Global Transition

SUMMARYInterleukin-2 (IL-2) is a small α-helical cytokine that regulates immune cell homeostasis through its recruitment to a high-affinity heterotrimeric receptor complex (IL-2Rα/IL-2Rβ/γc). IL-2 has been shown to have therapeutic efficacy for immune diseases by preferentially expanding distinct T-cell compartments, and several Treg-biasing anti-IL-2 antibodies have been developed for combination therapies. The conformational plasticity of IL-2 plays an important role in its biological actions by modulating the strength of receptor and drug interactions. Through a NMR analysis of milliseconds-timescale dynamics of free mIL-2 we identify a global transition to an auto-inhibitory conformation controlled by an α-helical capping “switch”. Binding to either an anti-mouse IL-2 mAb or a small molecule inhibitor near the AB loop induces changes in dynamics at the core of the structure, and perturbations of the capping hydrogen-bond network abrogate Ab binding by destabilizing the auto-inhibitory conformation. Our results highlight a paradigm for designing precision therapeutics targeting a continuum of IL-2 conformational states.

X-ray Crystallographic Study of Alkylammonium Anthracene-9-carboxylates as a Model for Fibrous Structure of Binary Anthracene Salt Gels

2004 ◽  
Vol 69 (6) ◽  
pp. 1292-1300 ◽  
Author(s):  
Tahahiro Tani ◽  
Kazuki Sada ◽  
Masatsugu Ayabe ◽  
Yuya Iwashita ◽  
Takanori Kishida ◽  
...  
Keyword(s):  
Alkyl Chain ◽  
Columnar Structure ◽  
Hydrogen Bond Network ◽  
One Dimensional ◽  
X Ray ◽  
Crystallographic Study ◽  
Alkylammonium Salts ◽  
Bond Network ◽  
Fibrous Assemblies ◽  
Long Alkyl Chain

Crystal structure of hexylammonium anthracene-9-carboxylate was investigated. The salt was arranged by a one-dimensional hydrogen bond network to form a columnar structure in the crystalline state. This columnar structure should be the model of fibrous assemblies in the organogels of anthracene-9-carboxylate alkylammonium salts having a long alkyl chain.

Halides of Macrocyclic Silver(II) Complexes: Crystal Structures with Hydrogen Bond Network and Reaction Kinetics of the Decomposition

2021 ◽  
pp. 120431
Author(s):  
Akinori Honda ◽  
Shunta Kakihara ◽  
Shuhei Ichimura ◽  
Kazuaki Tomono ◽  
Mina Matsushita ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Reaction Kinetics ◽  
Crystal Structures ◽  
Hydrogen Bond Network ◽  
Bond Network ◽  
Kinetics Of
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