The association of the surface array and the outer membrane of Deinococcus radiodurans

The hexagonal surface array of Deinococcus radiodurans strain Sark exhibits remarkably strong bonding of its subunits and association with the outer membrane. The array is not dissociated nor is it separated from the outer membrane by reagents that disrupt hydrogen bonds (urea, guanidine hydrochloride), ionic bonds (pH, LiCl, KCl, NaCl), disulphide bonds (β-mercaptoethanol, dithiothreitol), or chelating agents (ethylenediaminetetraacetic acid). Only disruption of the outer membrane with sodium dodecyl sulphate at room temperature separated the two layers. The isolated array was composed of a major protein of 115 000 molecular weight, a minor protein of 108 000 molecular weight, and no other polymers. Their amino acid profile was indicative of a protein, lacking proline, with a high proportion (51.2%, mole/mole) of polar amino acids. The electron-transparent layer between the hexagonal surface array and the outer membrane was still associated with the purified array, suggesting that the electron-transparen...