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Secondary structure and calcium-induced folding of the Clostridium thermocellum dockerin domain determined by NMR spectroscopy. Arch Biochem Biophys 2000 Jul 15;379(2):237-44

Date

07/19/2000

Pubmed ID

10898940

DOI

10.1006/abbi.2000.1882

Scopus ID

2-s2.0-0034661436   51 Citations

Abstract

Assembly of the cellulosome, a large, extracellular cellulase complex, depends upon docking of a myriad of enzymatic subunits to homologous receptors, or cohesin domains, arranged in tandem along a noncatalytic scaffolding protein. Docking to the cohesin domains is mediated by a highly conserved domain, dockerin (DS), borne by each enzymatic subunit. DS consists of two 22-amino-acid duplicated sequences, each bearing homology to the EF-hand calcium-binding loop. To compare the DS structure with that of the EF-hand helix-loop-helix motif, we analyzed the solution secondary structure of the DS from the cellobiohydrolase CelS subunit of the Clostridium thermocellum cellulosome using multidimensional heteronuclear NMR spectroscopy. The effect of Ca(2+)-binding on the DS structure was first investigated by using 2D (15)N-(1)H HSQC NMR spectroscopy. Changes in the spectra during Ca(2+) titration revealed that Ca(2+) induces folding of DS into its tertiary structure. This Ca(2+)-induced protein folding distinguishes DS from typical EF-hand-containing proteins. Sequential backbone assignments were determined for 63 of 69 residues. Analysis of the NOE connectivities and H(alpha) chemical shifts revealed that each half of the dockerin contains just one alpha-helix, comparable to the F-helix of the EF-hand motif. Thus, the structure of the DS Ca(2+)-binding subdomain deviates from that of the canonical EF-hand motif.

Author List

Lytle BL, Volkman BF, Westler WM, Wu JH

Author

Brian F. Volkman PhD Professor in the Biochemistry department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Calcium
Cellulase
Clostridium
EF Hand Motifs
Molecular Sequence Data
Nuclear Magnetic Resonance, Biomolecular
Protein Binding
Protein Folding
Protein Structure, Secondary
Protein Structure, Tertiary
Sequence Alignment
Sequence Homology, Amino Acid
Titrimetry
jenkins-FCD Prod-444 eb4ebd1a08581aba961d3befd3b851a3c3ec6b46