CetZ tubulin-like proteins control archaeal cell shape

• Published in: Nature (London) Vol. 519; no. 7543; pp. 362 - 365
• Main Authors: Duggin, Iain G., Aylett, Christopher H. S., Walsh, James C., Michie, Katharine A., Wang, Qing, Turnbull, Lynne, Dawson, Emma M., Harry, Elizabeth J., Whitchurch, Cynthia B., Amos, Linda A., Löwe, Jan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.03.2015; Nature Publishing Group
• Subjects: 14/28; 14/35; 14/63; 631/326/26; 631/80/128; Amino Acid Sequence; Archaeabacteria; Archaeal Proteins - chemistry; Archaeal Proteins - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Bacteriology; Cell Division; Cell Membrane - metabolism; Cell research; Cell Shape; Crystallography, X-Ray; Crystals; Cytoskeletal Proteins - chemistry; Cytoskeletal Proteins - metabolism; Haloferax volcanii - cytology; Haloferax volcanii - metabolism; Humanities and Social Sciences; Inactivation; letter; Models, Molecular; Molecular Sequence Data; Morphology; Motility; Movement; multidisciplinary; Mutation; Physiological aspects; Proteins; Science; Structure; Swimming; Tubulin - chemistry; Tubulin - metabolism; Tubulins
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature13983

The structure and function of CetZ, a protein related to both tubulin and FtsZ (the bacterial homologue of tubulin) from the archaeon Haloferax volcanii , is reported and its involvement in the control of cell shape uncovered; it appears that this family of proteins was involved in the control of cell shape long before the evolution of eukaryotes. Evolution of cell shaping proteins One of the distinguishing features of the eukaryotic cell is the cytoskeleton, a network of fibres that give the cell shape and are important in processes such as cell division. Bacteria do not have a cytoskeleton, but they do have a protein FtsZ, homologous with the eukaryotic protein tubulin, which establishes the cytokinetic ring which constricts during cell division. How the different roles of tubulin and FtsZ evolved is not known, but the answer could lie in the archaea, the third major domain of life. Iain Duggin et al . report the structure and function of CetZ, a protein related to both tubulin and FtsZ from the archaeon Haloferax volcanii , which is involved in the control of cell shape. The results suggest that this family of proteins was involved in the control of cell shape long before the evolution of eukaryotes. Tubulin is a major component of the eukaryotic cytoskeleton, controlling cell shape, structure and dynamics, whereas its bacterial homologue FtsZ establishes the cytokinetic ring that constricts during cell division 1 , 2 . How such different roles of tubulin and FtsZ evolved is unknown. Studying Archaea may provide clues as these organisms share characteristics with Eukarya and Bacteria 3 . Here we report the structure and function of proteins from a distinct family related to tubulin and FtsZ, named CetZ, which co-exists with FtsZ in many archaea. CetZ X-ray crystal structures showed the FtsZ/tubulin superfamily fold, and one crystal form contained sheets of protofilaments, suggesting a structural role. However, inactivation of CetZ proteins in Haloferax volcanii did not affect cell division. Instead, CetZ1 was required for differentiation of the irregular plate-shaped cells into a rod-shaped cell type that was essential for normal swimming motility. CetZ1 formed dynamic cytoskeletal structures in vivo , relating to its capacity to remodel the cell envelope and direct rod formation. CetZ2 was also implicated in H. volcanii cell shape control. Our findings expand the known roles of the FtsZ/tubulin superfamily to include archaeal cell shape dynamics, suggesting that a cytoskeletal role might predate eukaryotic cell evolution, and they support the premise that a major function of the microbial rod shape is to facilitate swimming.