NMR analysis of structure and dynamics of the cytosolic tails of integrin alpha IIb beta 3 in aqueous solution

• Published in: Biochemistry (Easton) Vol. 40; no. 25; p. 7498
• Main Authors: Ulmer, T S, Yaspan, B, Ginsberg, M H, Campbell, I D
• Format: Journal Article
• Language: English
• Published: United States 26.06.2001
• Subjects: Amino Acid Sequence; Amino Acid Substitution - genetics; Cytosol - chemistry; Integrins - chemistry; Integrins - genetics; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Nuclear Magnetic Resonance, Biomolecular - methods; Peptide Fragments - chemistry; Peptide Fragments - genetics; Platelet Glycoprotein GPIIb-IIIa Complex - chemistry; Platelet Glycoprotein GPIIb-IIIa Complex - genetics; Protein Structure, Secondary - genetics; Recombinant Fusion Proteins - chemistry; Solutions; Structure-Activity Relationship; Thermodynamics; Water
• ISSN: 0006-2960
• DOI: 10.1021/bi010338l

The structural and dynamic properties of the cytosolic tails of the adhesion receptor integrin alphaIIbbeta3, fused to a coiled-coil construct via (Gly)(3) linkers, were studied in aqueous solution by nuclear magnetic resonance (NMR) spectroscopy. Both tails were largely flexible and unstructured, although, in the beta3 tail, residues Arg(724)-Ala(735) have a propensity to form a helical structure and residues Asn(744)-Tyr(747) (NPLY) have a propensity to adopt reverse-turn conformations. The mutation beta3(Y747A) disrupted this reverse-turn tendency and markedly reduced the affinity of the head domain of the cytoskeletal protein, talin for the beta3 tail. Omission of the (Gly)(3) linker connecting the coiled-coiled helices and the integrin tails lead to helix propagation into the beta3 tail extending up to eight residues. A variety of different tail constructs were made and studied to reveal tail-tail interactions, but surprisingly no significant interactions between both tails could be detected within the context of our constructs. These results provide structural insight into a highly conserved beta tail motif (NPXY/F) required for integrin signaling and highlight a second transiently structured region (residues Arg(724)-Ala(735)), which might also be of functional significance.