The cell envelope of Thermoproteus tenax: three-dimensional structure of the surface layer and its role in shape maintenance

AUTOR(ES)

Wildhaber, I.

RESUMO

The sulphur-dependent archaebacterium Thermoproteus tenax has a cylindrical cell shape variable in length, but constant in diameter. Its whole surface is covered by a regular protein layer (S-layer). The lattice has p6 symmetry and a lattice constant of 32.8 nm. The three-dimensional reconstruction from a tilt series of isolated and negatively stained S-layer shows a complex mass distribution of the protein: a prominent, pillar-shaped protrusion is located at the 6-fold crystallographic axis with radiating arms connecting neighbouring hexamers in the vicinity of the 3-fold axis. The base vectors of the S-layer lattice have a preferred orientation with respect to the longitudinal axis of the cell. The layer can be seen as a helical structure consisting of a right-handed, two-stranded helix, with the individual chains running parallel. Supposing that new S-layer protein is inserted at lattice faults (wedge disclinations) near the poles, growing of the layer would then proceed by moving a disclination at the end of the helix. The constant shape of the cell, as well as the particular structure of the layer, strongly suggest that this S-layer has a shape-maintaining function.

Documentos Relacionados

• Three-dimensional structure of the tetragonal surface layer of Sporosarcina ureae.
• Three-dimensional structure of the regular tetragonal surface layer of Azotobacter vinelandii.
• Three-dimensional structure of the regularly constructed surface layer from Synechocystis sp. strain CLII.
• Three-dimensional structure of the regular surface glycoprotein layer of Halobacterium volcanii from the Dead Sea
• Pyruvate Kinase of the Hyperthermophilic Crenarchaeote Thermoproteus tenax: Physiological Role and Phylogenetic Aspects