The structure of the periplasmic FlaG-FlaF complex and its essential role for archaellar swimming motility.

Motility structures are vital in all three domains of life. In Archaea, motility is mediated by the archaellum, a rotating type IV pilus-like structure that is a unique nanomachine for swimming motility in nature. Whereas periplasmic FlaF binds the surface layer (S-layer), the structure, assembly and roles of other periplasmic components remain enigmatic, limiting our knowledge of the archaellum's functional interactions.

Cell Structure Changes in the Hyperthermophilic Crenarchaeon Sulfolobus islandicus Lacking the S-Layer.

Rediscovery of the ancient evolutionary relationship between archaea and eukaryotes has revitalized interest in archaeal cell biology. Key to the understanding of archaeal cells is the surface layer (S-layer), which is commonly found in but whose function is unknown. Here, we investigate the architecture and cellular roles of the S-layer in the hyperthermophilic crenarchaeon Electron micrographs of mutant cells lacking or both and confirm the absence of the outermost layer (SlaA), whereas cells with intact or partially or completely detached SlaA are observed for the Δ mutant.

The essential genome of the crenarchaeal model Sulfolobus islandicus.

Sulfolobus islandicus is a model microorganism in the TACK superphylum of the Archaea, a key lineage in the evolutionary history of cells. Here we report a genome-wide identification of the repertoire of genes essential to S. islandicus growth in culture.