The deoxyribonucleoprotein complex from the archaebacterium Methanosarcina barkeri: characterization and ultrastructural localization of the chromosomal protein MC1

Abstract

The Methanosarcina barkeri protein, methanogen chromosomal protein 1 (MC1), a basic polypeptide of 93 amino acid residues, has been localized in the DNA-rich areas on immunolabelled bacterial cryosections revealed with the protein A – gold method. This localization strongly supports the previous studies concerning the association of the protein MC1 with the DNA in vivo. In the M. barkeri deoxyribonucleoprotein complex, the protein MC1 accounts for about 90% of the total proteins, and the protein MC1 so DNA ratio (by weight) is equal to 0.11. Staphylococcal nuclease digestion data and microscopic observations have failed to reveal the presence of repeating structural units and suggest that the protein MC1 is unevenly distributed along the DNA.