title: Conservation and variability in Archaea: protein antigens with tandem repeats encoded by a cluster of genes with common motifs in Methanosarcina mazei S-6.
abstract: Three open reading frames, orf492, orf375 and orf783, were identified in a 5.9-kb DNA fragment from the genome of Methanosarcina mazei S-6 that code for proteins recognized by antibodies against cell-surface antigens. The deduced amino-acid (aa) sequences of orfs492 and 375, i.e., ORF492 and ORF375, contain seven and four copies of an approx. 42-aa repeat, respectively. The aa sequence of ORF783 contains nine copies of an approx. 85-aa repeat, one of which is also present once in each of the first two ORFs. The organization of the repeats is similar to that of some Gram+ cell-wall-associated proteins. Comparative analyses of aa sequences, compositions and hydropathy profiles of the archaeal ORFs showed similarity with surface (S-) layer and outer-membrane proteins of Bacteria and Archaea.
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000235:genetics*; D001483:Base Sequence; D017124:Conserved Sequence; D017020:Methanosarcina / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment
chemical_list: D000942:Antigens, Bacterial