Crystal structure of the flexible tandem repeat domain of bacterial cellulose synthesis subunit

Shingo Nojima, Ayumi Fujishima, Koji Kato, Kayoko Ohuchi, Nobutaka Shimizu, Kento Yonezawa, Kenji Tajima, Min Yao

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Abstract

Bacterial cellulose (BC) is synthesized and exported through the cell membrane via a large protein complex (terminal complex) that consists of three or four subunits. BcsC is a little-studied subunit considered to export BC to the extracellular matrix. It is predicted to have two domains: a tetratrico peptide repeat (TPR) domain and a β-barrelled outer membrane domain. Here we report the crystal structure of the N-terminal part of BcsC-TPR domain (Asp24-Arg272) derived from Enterobacter CJF-002. Unlike most TPR-containing proteins which have continuous TPR motifs, this structure has an extra α-helix between two clusters of TPR motifs. Five independent molecules in the crystal had three different conformations that varied at the hinge of the inserted α-helix. Such structural feature indicates that the inserted α-helix confers flexibility to the chain and changes the direction of the TPR super-helix, which was also suggested by structural analysis of BcsC-TPR (Asp24-Leu664) in solution by size exclusion chromatography-small-angle X-ray scattering. The flexibility at the α-helical hinge may play important role for exporting glucan chains.

Original languageEnglish
Article number13018
JournalScientific Reports
Volume7
Issue number1
DOIs
Publication statusPublished - Dec 1 2017
Externally publishedYes

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Cite this

Nojima, S., Fujishima, A., Kato, K., Ohuchi, K., Shimizu, N., Yonezawa, K., Tajima, K., & Yao, M. (2017). Crystal structure of the flexible tandem repeat domain of bacterial cellulose synthesis subunit. Scientific Reports, 7(1), [13018]. https://doi.org/10.1038/s41598-017-12530-0