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          Institute: MPI für Entwicklungsbiologie     Collection: Abteilung 2 - Biochemistry (E. Izaurralde)     Display Documents



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ID: 460590.0, MPI für Entwicklungsbiologie / Abteilung 2 - Biochemistry (E. Izaurralde)
A coiled-coil motif that sequesters ions to the hydrophobic core
Authors:Hartmann, M. D.; Ridderbusch, O.; Zeth, K.; Albrecht, R.; Testa, O.; Woolfson, D. N.; Sauer, G.; Dunin-Horkawicz, S.; Lupas, A. N.; Alvarez, B. H.
Date of Publication (YYYY-MM-DD):2009-10-06
Title of Journal:Proc Natl Acad Sci U S A
Volume:106
Issue / Number:40
Start Page:16950
End Page:16955
Review Status:not specified
Audience:Not Specified
Abstract / Description:Most core residues of coiled coils are hydrophobic. Occasional polar residues are thought to lower stability, but impart structural specificity. The coiled coils of trimeric autotransporter adhesins (TAAs) are conspicuous for their large number of polar residues in position d of the core, which often leads to their prediction as natively unstructured regions. The most frequent residue, asparagine (N@d), can occur in runs of up to 19 consecutive heptads, frequently in the motif [I/V]xxNTxx. In the Salmonella TAA, SadA, the core asparagines form rings of interacting residues with the following threonines, grouped around a central anion. This conformation is observed generally in N@d layers from trimeric coiled coils of known structure. Attempts to impose a different register on the motif show that the asparagines orient themselves specifically into the core, even against conflicting information from flanking domains. When engineered into the GCN4 leucine zipper, N@d layers progressively destabilized the structure, but zippers with 3 N@d layers still folded at high concentration. We propose that N@d layers maintain the coiled coils of TAAs in a soluble, export-competent state during autotransport through the outer membrane. More generally, we think that polar motifs that are both periodic and conserved may often reflect special folding requirements, rather than an unstructured state of the mature proteins.
Free Keywords:Adhesins, Bacterial/*chemistry/genetics/metabolism; *Amino Acid Motifs; Amino Acid Sequence; Asparagine/chemistry/genetics/metabolism; Binding Sites; Biological Transport; Circular Dichroism; Crystallography, X-Ray; Hydrophobicity; Ions/*chemistry/metabolism; Leucine Zippers; Models, Molecular; Molecular Sequence Data; Protein Conformation; Protein Multimerization; *Protein Structure, Tertiary; Salmonella enterica/genetics/metabolism; Sequence Homology, Amino Acid; Threonine/chemistry/genetics/metabolism
External Publication Status:published
Document Type:Article
Communicated by:root
Affiliations:MPI für Entwicklungsbiologie
External Affiliations:%G eng
Identifiers:ISSN:1091-6490 (Electronic) 1091-6490 (Linking) %R 0907... [ID No:1]
URL:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=... [ID No:2]
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