Toward the development of genetic tools for Planctomycetes

Abstract

Members of the phylum Planctomycetes possess a complex cell biology, including compartmentalization of their cytosol, elaborate life cycles, asymmetric cell division through budding, and construction of a proteinaceous cell wall that lacks peptidoglycan. That they perform endocytosis-like protein uptake using molecular components structurally similar to their eukaryotic counterparts prompted the controversial hypothesis that their ancestors participated in the evolution of the eukaryotic cell plan. In-depth analysis of these intriguing traits has been hampered by the lack of genetic tools for planctomycetes. Here we first introduce three model planctomycetes-Gemmata obscuriglobus, Rhodopirellula baltica, and Planctomyces limnophilus-by describing aspects of their biology that are particularly relevant to genetic tool development. We then summarize the methods and tools for genetic analysis that have recently become available for planctomycetes. Lastly, we briefly outline the tools most urgently needed and suggest potentially fruitful directions for their development, thus opening the door to understanding the fascinating biology of the planctomycetes at a molecular level.