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Updated: May 16, 2026

Membrane-SPINE: A Biochemical Tool to Identify Protein-protein Interactions of Membrane Proteins In Vivo
Published on: November 7, 2013
Structural properties of the tubular appendage spinae from marine bacterium Roseobacter sp. strain YSCB
A Bernadac1, L-F Wu, C-L Santini
1Service de Microscopie Electronique, Institut de Microbiologie de la Méditerranée, Aix-Marseille University , CNRS, 31 chemin Joseph Aiguier, 13402 Marseille cedex 20, France.
Abstract:
Spinae are tubular surface appendages broadly found in Gram-negative bacteria. Little is known about their architecture, function or origin. Here, we report structural characterization of the spinae from marine bacteria Roseobacter sp. YSCB. Electron cryo-tomography revealed that a single filament winds into a hollow flared base with progressive change to a cylinder. Proteinase K unwound the spinae into proteolysis-resistant filaments. Thermal treatment ripped the spinae into ribbons that were melted with prolonged heating. Circular dichroism spectroscopy revealed a dominant beta-structure of the spinae. Differential scanning calorimetry analyses showed three endothermic transformations at 50-85°C, 98°C and 123°C, respectively. The heating almost completely disintegrated the spinae, abolished the 98°C transition and destroyed the beta-structure. Infrared spectroscopy identified the amide I spectrum maximum at a position similar to that of amyloid fibrils. Therefore, the spinae distinguish from other bacterial appendages, e.g. flagella and stalks, in both the structure and mechanism of assembly.
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