Surface Appendages of Archaea: Structure, Function, Genetics and Assembly

Abstract

Organisms representing diverse subgroupings of the Domain Archaea are known to possess unusual surface structures. These can include ones unique to Archaea such as cannulae and hami as well as archaella (archaeal flagella) and various types of pili that superficially resemble their namesakes in Bacteria, although with significant differences. Major advances have occurred particularly in the study of archaella and pili using model organisms with recently developed advanced genetic tools. There is common use of a type IV pili-model of assembly for several archaeal surface structures including archaella, certain pili and sugar binding structures termed bindosomes. In addition, there are widespread posttranslational modifications of archaellins and pilins with N-linked glycans, with some containing novel sugars. Archaeal surface structures are involved in such diverse functions as swimming, attachment to surfaces, cell to cell contact resulting in genetic transfer, biofilm formation, and possible intercellular communication. Sometimes functions are co-dependent on other surface structures. These structures and the regulation of their assembly are important features that allow various Archaea, including thermoacidophilic, hyperthermophilic, halophilic, and anaerobic ones, to survive and thrive in the extreme environments that are commonly inhabited by members of this domain.

Exceptionally widespread nanomachines composed of type IV pilins: the prokaryotic Swiss Army knives

“…As confirmed by the wealth of interesting data coming from archaeal Tff (Jarrell et al. , 2013), future research should not only favour the ‘historic’ models (although there is still plenty to be learned in T2SS, Bfp, Tcp or Neisseria and P. aeruginosa Tfpa) but should be extended to new models, more distant from an evolutionary point of view. An in-depth study of Gram-positive Tfp would be for example of great interest as such bacteria are inherently ‘simpler’ because of the absence of an outer membrane (Melville and Craig 2013).…”

“…, 2007; Jarrell et al. , 2013). Importantly, these features distinguish class III signal peptides, which are processed by a dedicated prepilin peptidase after the conserved Gly on the cytoplasmic side of the membrane (Nunn and Lory 1991) (Fig.…”

The Confluence of Heavy Metal Biooxidation and Heavy Metal Resistance: Implications for Bioleaching by Extreme Thermoacidophiles

“…Results showed variations in EPS glycoconjugates for three archaeal species and that various substrates induce different EPS glycoconjugates, similar to the flexibility of bacteria [281,334]. For more information on the aspects of other archaeal biofilms, informative reviews are available [331,[335][336][337][338].…”

N-Linked Glycosylation in Archaea: a Structural, Functional, and Genetic Analysis

“…Our current understanding of N-glycosylation in the methanogens has come from a significant body of work addressing the structure and genetics of this PTM in two species of Methanococcus, namely, M. voltae and M. maripaludis (104)(105)(106)(107). In addition, in vitro biochemical work using purified enzymes has further con-tributed to our understanding of the process in this group of Archaea (108)(109)(110).…”