Refereed journal article or data article (A1)
A Novel Structural Unit in the N-terminal Region of Filamins
List of Authors: Sethi R, Seppala J, Tossavainen H, Ylilauri M, Ruskamo S, Pentikainen OT, Pentikainen U, Permi P, Ylanne J
Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Publication year: 2014
Journal: Journal of Biological Chemistry
Journal name in source: JOURNAL OF BIOLOGICAL CHEMISTRY
Journal acronym: J BIOL CHEM
Volume number: 289
Issue number: 12
Start page: 8588
End page: 8598
Number of pages: 11
ISSN: 0021-9258
DOI: http://dx.doi.org/10.1074/jbc.M113.537456
Abstract
Background: Filamins are actin cross-linking and signaling scaffolding proteins where C-terminal domains have inter-domain interactions but little is known about the N-terminal domains. Results: Crystal structures of N-terminal domains 3-5 reveal novel domain packing and interaction details of domain 4. Conclusion: Domain 4 is stabilized by interaction with domain 5. Significance: Here, inter-domain interactions positively regulate domain 4 interactions with ligands.Immunoglobulin-like (Ig) domains are a widely expanded superfamily that act as interaction motifs or as structural spacers in multidomain proteins. Vertebrate filamins (FLNs), which are multifunctional actin-binding proteins, consist of 24 Ig domains. We have recently discovered that in the C-terminal rod 2 region of FLN, Ig domains interact with each other forming functional domain pairs, where the interaction with signaling and transmembrane proteins is mechanically regulated by weak actomyosin contraction forces. Here, we investigated if there are similar inter-domain interactions around domain 4 in the N-terminal rod 1 region of FLN. Protein crystal structures revealed a new type of domain organization between domains 3, 4, and 5. In this module, domains 4 and 5 interact rather tightly, whereas domain 3 has a partially flexible interface with domain 4. NMR peptide titration experiments showed that within the three-domain module, domain 4 is capable for interaction with a peptide derived from platelet glycoprotein Ib. Crystal structures of FLN domains 4 and 5 in complex with the peptide revealed a typical sheet augmentation interaction observed for many FLN ligands. Domain 5 was found to stabilize domain 4, and this could provide a mechanism for the regulation of domain 4 interactions.
Background: Filamins are actin cross-linking and signaling scaffolding proteins where C-terminal domains have inter-domain interactions but little is known about the N-terminal domains. Results: Crystal structures of N-terminal domains 3-5 reveal novel domain packing and interaction details of domain 4. Conclusion: Domain 4 is stabilized by interaction with domain 5. Significance: Here, inter-domain interactions positively regulate domain 4 interactions with ligands.Immunoglobulin-like (Ig) domains are a widely expanded superfamily that act as interaction motifs or as structural spacers in multidomain proteins. Vertebrate filamins (FLNs), which are multifunctional actin-binding proteins, consist of 24 Ig domains. We have recently discovered that in the C-terminal rod 2 region of FLN, Ig domains interact with each other forming functional domain pairs, where the interaction with signaling and transmembrane proteins is mechanically regulated by weak actomyosin contraction forces. Here, we investigated if there are similar inter-domain interactions around domain 4 in the N-terminal rod 1 region of FLN. Protein crystal structures revealed a new type of domain organization between domains 3, 4, and 5. In this module, domains 4 and 5 interact rather tightly, whereas domain 3 has a partially flexible interface with domain 4. NMR peptide titration experiments showed that within the three-domain module, domain 4 is capable for interaction with a peptide derived from platelet glycoprotein Ib. Crystal structures of FLN domains 4 and 5 in complex with the peptide revealed a typical sheet augmentation interaction observed for many FLN ligands. Domain 5 was found to stabilize domain 4, and this could provide a mechanism for the regulation of domain 4 interactions.