Structure, organization, and expression of genes coding for envelope components in the archaeon Methanosarcina mazei S-6
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© Springer-Verlag 1998
O R I G I N A L PA P E R
Linda E. Mayerhofer · Everly Conway de Macario · Rong Yao · Alberto J. L. Macario
Structure, organization, and expression of genes coding for envelope components in the archaeon Methanosarcina mazei S-6
Received: 26 June 1997 / Accepted: 5 November 1997
Abstract The antigenic mosaics of archaeal species are complex and lead to the distinction of different immunotypes. We began the dissection of the antigenic mosaic of the methanogen Methanosarcina mazei S-6 by gene cloning and sequencing. The analysis of the sequence, organization, and in vitro (heterologous) and in vivo expression of two three-gene clusters that encode proteins localized to the cell envelope and that are recognized by antibodies for surface structures is presented in this report. The amino acid sequences and compositions share characteristics with S-layer proteins and, most notably, have repeats of conserved sequences and secondary structures. Expressed genes produced proteins with a tendency to oligomerize, and one of these proteins was susceptible to breakdown at regular intervals. Altogether, the data reveal a modular system (clusters of homologous genes, proteins of similar sequences with conserved repeats) seemingly suitable for assembling an enormous variety of final molecular structures by rearranging and combining genes, proteins, and repeats, and thus generate the observed wide spectrum of antigenic diversity. Key words Archaea · Cell envelope genes · Heterologous expression · In vivo expression · Methanosarcina mazei · Cell envelope proteins · Repeats · S-layer · Antigenic diversity
This paper is dedicated to Dr. Mary C. Pangborn, the discoverer of cardiolipin at the Wadsworth Center, New York State Department of Health, on the occasion of her 90th birthday L. E. Mayerhofer · E. Conway de Macario (Y) · R. Yao · Alberto J. L. Macario Wadsworth Center, Division of Molecular Medicine, New York State Department of Health and Department of Biomedical Sciences, School of Public Health, The University at Albany, Albany, NY 12201-0509, USA Tel. + 1-518-474-2781; Fax + 1-518-474-1213 or -8590 e-mail: [email protected]
Introduction Cell envelopes within the phylogenetic domain Archaea are varied, reflecting the diversity of archaeal species (Baumeister and Lembcke 1992). Even within a single archaeal subgroup such as the methanogens, the cell envelope heterogeneity is remarkable. This cell envelope heterogeneity is mirrored in the antigenic diversity of methanogens and in the complexity of their antigenic mosaics (Conway de Macario and Macario 1986). Methanosarcinas are a good example. The antigenic mosaic of individual strains is constituted of multiple antigenic determinants or epitopes and allows distinction of immunotypes (Garberi et al. 1985). In Methanosarcina mazei S-6 with three different morphologic stages (i.e., packets, lamina, and single cells), another level of diversity is observed. The cells are circumscribed by an S-layer that is surrounded in packets and lamina by a complex
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