Structure of bacterial cellulose synthase subunit D octamer with four inner passageways

Song Qing Hu, Yong Gui Gao, Kenji Tajima, Naoki Sunagawa, Yong Zhou, Shin Kawano, Takaaki Fujiwara, Takanori Yoda, Daisuke Shimura, Yasuharu Satoh, Masanobu Munekata, Isao Tanaka, Min Yao

Research output: Contribution to journalArticlepeer-review

94 Citations (Scopus)

Abstract

The cellulose synthesizing terminal complex consisting of subunits A, B, C, and D in Acetobacter xylinum spans the outer and inner cell membranes to synthesize and extrude glucan chains, which are assembled into subelementary fibrils and further into a ribbon. We determined the structures of subunit D (AxCeSD/AxBcsD) with both N- and C-terminal His6 tags, and in complex with cellopentaose. The structure of AxCeSD shows an exquisite cylinder shape (height: ∼65 Å, outer diameter: ∼90 Å, and inner diameter: ∼25 Å) with a right-hand twisted dimer interface on the cylinder wall, formed by octamer as a functional unit. All N termini of the octamer are positioned inside the AxCeSD cylinder and create four passageways. The location of cellopentaoses in the complex structure suggests that four glucan chains are extruded individually through their own passageway along the dimer interface in a twisted manner. The complex structure also shows that the N-terminal loop, especially residue Lys6, seems to be important for cellulose production, as confirmed by in vivo assay using mutant cells with axcesD gene disruption and N-terminus truncation. Taking all results together, a model of the bacterial terminal complex is discussed.

Original languageEnglish
Pages (from-to)17957-17961
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number42
DOIs
Publication statusPublished - 2010 Oct 19
Externally publishedYes

Keywords

  • Cellulose biosynthesis
  • Crystal structure

ASJC Scopus subject areas

  • General

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