Burghardt, Tillmann and Näther, Daniela J. and Junglas, Benjamin and Huber, Harald and Rachel, Reinhard (2007) The dominating outer membrane protein of the hyperthermophilic Archaeum Ignicoccus hospitalis: a novel pore-forming complex. Molecular microbiology 63 (1), pp. 166-176.
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The membrane protein Imp1227 (Ignicoccus outer membrane protein; Imp1227) is the main protein constituent of the unique outer sheath of the hyperthermophilic, chemolithoautotrophic Archaeum Ignicoccus hospitalis. This outer sheath is the so far only known example for an asymmetric bilayer among the Archaea and is named 'outer membrane'. With its molecular mass of only 6.23 kDa, Imp1227 is found to be incorporated into the outer membrane in form of large, stable complexes. When separated by SDS-PAGE, they exhibit apparent masses of about 150, 50, 45 and 35 kDa. Dissociation into the monomeric form is achieved by treatment with SDS-containing solutions at temperatures at or above 113 degrees C. Electron micrographs of negatively stained samples confirm that isolated membranes are tightly packed with round complexes, about 7 nm in diameter, with a central, stain-filled 2 nm pore; a local two-dimensional crystalline arrangement in form of small patches can be detected by tomographic reconstruction. The comparison of the nucleotide and amino acid sequence of Imp1227 with public databases showed no reliable similarities with known proteins. Using secondary structure prediction and molecular modelling, an alpha-helical transmembrane domain is proposed; for the oligomer, a ring-shaped nonamer with a central 2 nm pore is a likely arrangement.
|Institutions:||Biology, Preclinical Medicine > Institut für Biochemie, Genetik und Mikrobiologie > Lehrstuhl für Mikrobiologie > Prof. Dr. Michael Thomm|
|Subjects:||500 Science > 570 Life sciences|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||15 Mar 2010 07:28|
|Last Modified:||15 Mar 2010 07:28|