Search results for "Helix interaction"
showing 4 items of 4 documents
Small Residues Inhibit Homo-Dimerization of the Human Carbonic Anhydrase XII Transmembrane Domain
2021
Amino acids with small side chains and motifs of small residues in a distance of four are rather abundant in human single-span transmembrane helices. While interaction of such helices appears to be common, the role of the small residues in mediating and/or stabilizing transmembrane helix oligomers remains mostly elusive. Yet, the mere existence of (small)xxx(small) motifs in transmembrane helices is frequently used to model dimeric TM helix structures. The single transmembrane helix of the human carbonic anhydrases XII contains a large number of amino acids with small side chains, and critical involvement of these small amino acids in dimerization of the transmembrane domain has been sugges…
A Ser residue influences the structure and stability of a Pro-kinked transmembrane helix dimer
2012
AbstractWhen localized adjacent to a Pro-kink, Thr and Ser residues can form hydrogen bonds between their polar hydroxyl group and a backbone carbonyl oxygen and thereby modulate the actual bending angle of a distorted transmembrane α-helix. We have used the homo-dimeric transmembrane cytochrome b559′ to analyze the potential role of a highly conserved Ser residue for assembly and stabilization of transmembrane proteins. Mutation of the conserved Ser residue to Ala resulted in altered heme binding properties and in increased stability of the holo-protein, most likely by tolerating subtle structural rearrangements upon heme binding. The results suggest a crucial impact of an intrahelical Ser…
Six amino acids define a minimal dimerization sequence and stabilize a transmembrane helix dimer by close packing and hydrogen bonding
2013
AbstractDistinct amino acid sequences have been described to mediate oligomerization of transmembrane α-helices. However, as the sequence context is crucial to determine specificity in transmembrane helix–helix interaction, the question arises how small a sequence can be without losing specificity. In the present analysis, six amino acids have been identified in the PsbF transmembrane helix dimer, which form the contact region of two interacting helices and are directly involved in helix–helix interactions. However, individual amino acids within the complex sequence pattern only together ensure sequence specificity of the analyzed transmembrane helix–helix interactions by mediating close pa…
The membrane environment modulates self-association of the human GpA TM domain--implications for membrane protein folding and transmembrane signaling.
2010
Abstract The influence of lipid bilayer properties on a defined and sequence-specific transmembrane helix–helix interaction is not well characterized yet. To study the potential impact of changing bilayer properties on a sequence-specific transmembrane helix–helix interaction, we have traced the association of fluorescent-labeled glycophorin A transmembrane peptides by fluorescence spectroscopy in model membranes with varying lipid compositions. The observed changes of the glycophorin A dimerization propensities in different lipid bilayers suggest that the lipid bilayer thickness severely influences the monomer–dimer equilibrium of this transmembrane domain, and dimerization was most effici…