The incredible path of myxobacteria towards aggregative multicellularity

Abstract

When reviewing developmental biology, it is imperative to mention the main prokaryote model for the study of mechanisms involved in cell growth, cell differentiation and morphogenesis, Myxobacteria. These Gram-negative δ-proteobacteria, mainly associated with surface soil, show a complex life cycle that culminates, when cells are nutritionally deprived, with the formation of multicellular structures termed fruiting bodies. These multicellular structures of different size, shape, and form among the Myxococcales order, can be composed of different cell types including sporulating cells or myxospores, within the fruiting body, and peripheral rods. In addition, some cells seem to undergo a process of autolysis for the benefit of the population by providing nutrients. Fruiting bodies are not static and previously to its maturation, numerous cells can move into and out of cellular aggregates. The regulation of fruiting bodies development involves a complex and non-redundant set of pathways controlled by a wide number of one-or two-component signalling systems, chemotaxis-like systems or extracytoplasmic function (ECF) sigma factors, encoded by their large genome. Also, many protein kinases are implicated at post-transcriptional level. In this chapter, we will travel along the fascinating path of Myxobacteria from their unicellular state to multicellular development that carries implicit mechanisms of social behaviour and motility and therefore cell to cell communication.