Solution structure of a type I dockerin domain, a novel prokaryotic, extracellular calcium-binding domain
| Autor: | B L, Lytle, B F, Volkman, W M, Westler, M P, Heckman, J H, Wu |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Clostridium
Models Molecular Binding Sites Chromosomal Proteins Non-Histone Molecular Sequence Data Nuclear Proteins Cell Cycle Proteins Protein Structure Tertiary Fungal Proteins Cellulase Cellulose 1 4-beta-Cellobiosidase Calcium Amino Acid Sequence EF Hand Motifs Nuclear Magnetic Resonance Biomolecular Sequence Alignment Protein Binding |
| Zdroj: | Journal of molecular biology. 307(3) |
| ISSN: | 0022-2836 |
| Popis: | The type I dockerin domain is responsible for incorporating its associated glycosyl hydrolase into the bacterial cellulosome, a multienzyme cellulolytic complex, via its interaction with a receptor domain (cohesin domain) of the cellulosomal scaffolding subunit. The highly conserved dockerin domain is characterized by two Ca(2+)-binding sites with sequence similarity to the EF-hand motif. Here, we present the three-dimensional solution structure of the 69 residue dockerin domain of Clostridium thermocellum cellobiohydrolase CelS. Torsion angle dynamics calculations utilizing a total of 728 NOE-derived distance constraints and 79 torsion angle restraints yielded an ensemble of 20 structures with an average backbone r.m.s.d. for residues 5 to 29 and 32 to 66 of 0.54 A from the mean structure. The structure consists of two Ca(2+)-binding loop-helix motifs connected by a linker; the E helices entering each loop of the classical EF-hand motif are absent from the dockerin domain. Each dockerin Ca(2+)-binding subdomain is stabilized by a cluster of buried hydrophobic side-chains. Structural comparisons reveal that, in its non-complexed state, the dockerin fold displays a dramatic departure from that of Ca(2+)-bound EF-hand domains. A putative cohesin-binding surface, comprised of conserved hydrophobic and basic residues, is proposed, providing new insight into cellulosome assembly. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect