Keywords: protein transport, type IV pili, flagella, S-layer, biofilm formation, archaea
Biosynthesis and function of prokaryotic cell envelopes and their surface structures
Bacteria and archaea have complex cell envelopes that have several important functions, including providing a barrier that protects the cytoplasm from the environment. Along with its associated proteinaceous structures, it also ensures cell stability, facilitates motility and mediates adherence to biotic and abiotic surfaces. Although archaea are ubiquitous, present in all habitats examined thus far, including the human microbiome, compared to the bacteria, little is yet known about this domain of life. Using the genetically and biochemically amenable model archaeon Haloferax volcanii, my lab employs well-established techniques of molecular biology, biochemistry, and microscopy, as well as cutting edge technologies, such as RNAseq, to characterize the unique archaeal, as well as the highly conserved, aspects of archaeal cell surface biology.
Our lab’s extensive characterization of the evolutionarily conserved Sec pathway, as well as the Tat pathway, advanced the understanding of protein transport across both domains of prokaryotes. Exciting results from our recent analyses of cell surface anchoring strategies of archaeal proteins have uncovered a seemingly unique archaeal surface anchoring strategy and also revealed a novel membrane anchoring mechanism that is conserved between archaea and bacteria. Furthermore, our analyses of archaeal surface filaments led to the identification of previously unknown roles of type IV pilins in the regulation of early steps in biofilm formation (Fig. 1). The lab has used the data gleaned from these in vivo studies to develop novel software programs, as well as to improve existing ones, that predict the substrates that use specific transport and cell surface anchoring pathways. Information gleaned from these studies has invariably been used to further develop our understanding of the molecular mechanisms that have allowed haloarchaea to adapt to high salt conditions and could shed light on how alien life may withstand extreme conditions, such as the highly salty fluids on Mars (see Astrobiology-Magazine article).
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