Beyond the bacterium: planctomycetes challenge our concepts of microbial structure and function

Abstract

Planctomycetes form a distinct phylum of the domain Bacteria and possess unusual features such as intracellular compartmentalization and a lack of peptidoglycan in their cell walls. Remarkably, cells of the genus Gemmata even contain a membrane-bound nucleoid analogous to the eukaryotic nucleus. Moreover, the so-called 'anammox' planctomycetes have a unique anaerobic, autotrophic metabolism that includes the ability to oxidize ammonium; this process is dependent on a characteristic membrane-bound cell compartment called the anammoxosome, which might be a functional analogue of the eukaryotic mitochondrion. The compartmentalization of planctomycetes challenges our hypotheses regarding the origins of eukaryotic organelles. Furthermore, the recent discovery of both an endocytosis-like ability and proteins homologous to eukaryotic clathrin in a planctomycete marks this phylum as one to watch for future research on the origin and evolution of the eukaryotic cell.

Regarding the presence of membrane coat proteins in bacteria: Confusion? What confusion?

“…nup85 and nup133) [1]. We and others have suggested that some of these bacterial features are related by vertical descent to their archaeal or eukaryotic counterparts, leading to alternative eukaryogenesis hypotheses [2][3][4][5][6].…”

The 1st EMBO workshop on PVC bacteria—Planctomycetes–Verrucomicrobia–Chlamydiae superphylum: Exceptions to the bacterial definition?

“…These exceptional features include a complex and dynamic endomembrane system with no equivalent in prokaryotes, most clearly displayed in the phylum Planctomycetes but also in Verrucomicrobia and Lentisphaerae. It also includes many other features, such as tubulin in the case of some Verrucomicrobia; sterols in the case of the planctomycete Gemmata obscuriglobus; absence of peptidoglycan in planctomycetes (where it is replaced by protein in the cell wall); some verrucomicrobia and the chlamydiae (so far as has been determined); the lack in planctomycetes and chlamydiae of the otherwise ubiquitous FtsZ protein and FtsZ-dependent system for cell division widespread in all other bacteria; presence of C1 transfer enzymes in many planctomycetes; and the unique anaerobic ammonium-oxidizing metabolism in anammox planctomycetes (Fuerst and Sagulenko 2011).…”

“…These controversies have, in the wider evolutionary context, been related to the question of whether eukaryote-like features in the PVC superphylum are evolutionarily homologous or analogous to those of domain Eukarya and Archaea members (Devos 2012;Devos and Reynaud 2010;Forterre 2010;Forterre and Gribaldo 2010;Fuerst and Sagulenko 2011;McInerney et al 2011;Reynaud and Devos 2011).…”

“…The PVC superphylum includes the phylum Planctomycetes, a group of ubiquitous bacteria comprising both aerobic and anaerobic representatives that dwell in soil, fresh water, the oceans, and most other locations in which microbial biodiversity has been analyzed (Fuerst and Sagulenko 2011); the phylum Verrucomicrobia, which includes a small number of species isolated from fresh water, soil and human feces and by implication the gastrointestinal tract (Derrien et al 2004;Hedlund et al 1997); the phylum Chlamydiae, whose members are obligate intracellular pathogens; the Poribacteria, found so far only as obligate symbiont of sponges (Fieseler et al 2004) the phylum Lentisphaerae, which includes marine microorganisms and human gut microbiota (Cho et al 2004) and the OP3 candidate phylum which contains no cultured representative but occurs in anoxic habitats (Glöckner et al 2010). The inference that those organisms form a natural group was initially based on 16S rRNA phylogenetic analysis (Wagner and Horn 2006).…”

Geographic distribution at subspecies resolution level: closely related Rhodopirellula species in European coastal sediments

“…Members of this group show some exceptional properties, such as budding reproduction and species-specific intracellular membrane-separated compartmentalization (Fuerst and Sagulenko, 2011;Speth et al, 2012) and they are proposed to have an important role in the global carbon and nitrogen cycles (Strous et al, 2002;Glöckner et al, 2003). The genus Rhodopirellula and the type strain Rhodopirellula baltica SH1 T were first described by Schlesner et al (2004).…”