Structure, organization, and expression of genes coding for envelope components in the archaeon Methanosarcina mazei S-6

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.

‘ARMAN’ archaea depend on association with euryarchaeal host in culture and in situ

“…However, in some cases the surface layer proteins may also help in cell–cell association 41, 42 . The Mia14 surface layer likely possesses a very complex and unique architecture, consisting of at least eight strain-specific secreted surface proteins.…”

Reveromycin A biosynthesis uses RevG and RevJ for stereospecific spiroacetal formation

“…The proposed dihydroxy ketone precursors for these compounds might be nonenzymatically cyclized to form thermodynamically and electrostatically preferred spiroacetals. RevJ included seven YVTN repeat-like domains, which are found in archaeal surface layer proteins (SLPs) 45 . Because the crystal structure of the SLP shows seven YVTN β-propeller domains 46 , RevJ might construct a similar scaffold.…”

Characterization of Inverted Membrane Vesicles from the Halophilic Archaeon Haloferax volcanii

“…Previous attempts at preparation of archaeal IMVs have met with mixed success, apparently due to the presence of a protein-based surface layer. Indeed, preparation of IMVs from Methanosarcina mazei, one of the two archaeal strains from which IMVs are currently available, involves prior proteolytic digestion of surface structures [2,30]. The S-layer glycoprotein has also been cited as the agent responsible for the inability to obtain IMVs from other archaeal strains, including Sulfolobus acidocaldarius [28,36].…”