Two billion years of actin. Meeting on cytoskeletal dynamics: from cell biology to developmental disease.

Abstract

This meeting began with personal retrospective presentations from two of the founding fathers of European cytoskeletal research—V. Small (Vienna, Austria) and U. Lindberg (Stockholm, Sweden)—to commemorate the thirtieth anniversary of the first definitive publication to establish the existence of an actin cytoskeleton in non‐muscle cells (Lazarides & Weber, 1974). ### Ancient cytoskeletons Whereas other meetings often feature an occasional talk on the prokaryotic cytoskeleton, this meeting devoted a whole session to several aspects of our present knowledge of these ancient systems. This was well received and served as a useful reminder that the cytoskeleton is not just the domain of eukaryotic cell biologists. J. Errington (Oxford, UK) introduced the topic of the bacterial cytoskeleton and reviewed earlier studies that showed the filamentous nature of the ancient bacterial actin proteins MreB and Mbl (MreB‐like). As he pointed out, although we have known about actin filaments for 30 years, they have almost certainly existed for more than two billion years. Many early studies on bacterial cell shape indicated that the cell wall alone conveyed the information that was required for morphology. However, the finding that some of the genes that had been identified in mutational cell‐shape screens encoded protein products that resided in the cytosol meant that this idea had to be revisited. Errington and colleagues are now investigating the functions of the Mbl protein, which is one of three MreB homologues in Bacillus subtilis . They have used fluorescence recovery after photobleaching (FRAP), which is a technically demanding technique in an organism as small as a bacterium, to show that the helical Mbl cables are dynamic structures in vivo (Fig 1). The kinetics of recovery indicate that this is achieved through turnover from unbleached parts of the cell. These studies also imply that the organization of the cables is not likely to be …