Abstract
Polyphosphates (polyP) are polymers of orthophosphate residues linked by high-energy phosphoanhydride bonds that are important in all domains of life and function in many different processes, including biofilm development. To study the effect of polyP in archaeal biofilm formation, our previously described Sa. solfataricus polyP (−) strain and a new polyP (−) S. acidocaldarius strain generated in this report were used. These two strains lack the polymer due to the overexpression of their respective exopolyphosphatase gene (ppx). Both strains showed a reduction in biofilm formation, decreased motility on semi-solid plates and a diminished adherence to glass surfaces as seen by DAPI (4′,6-diamidino-2-phenylindole) staining using fluorescence microscopy. Even though arlB (encoding the archaellum subunit) was highly upregulated in S. acidocardarius polyP (−), no archaellated cells were observed. These results suggest that polyP might be involved in the regulation of the expression of archaellum components and their assembly, possibly by affecting energy availability, phosphorylation or other phenomena. This is the first evidence indicating polyP affects biofilm formation and other related processes in archaea.
Highlights
Polyphosphates are polymers of inorganic orthophosphate that can reach hundreds to thousands of residues in size
Sa. solfataricus biofilms of polyP (−) and background strains at days 2 and 3 of growth showed significant differences as indicated by the 570/600 nm index (Figure 1, 570/600 ratio panel)
The results presented here suggest that similar to what is known in bacteria, polyP in Sulfolobales functions in biofilm formation and motility by regulating
Summary
Polyphosphates (polyP) are polymers of inorganic orthophosphate that can reach hundreds to thousands of residues in size. PPK and PPX are the two main enzymes related to polyP metabolism in Prokaryotes. PPK synthesizes polyP, consuming ATP as the polyP chain grows, generating ADP and polyP (n+1) as final products. PPX degrades polyP starting from its last phosphate group, releasing Pi and polyP (n−1) in the process [1]. PPX has been identified either by experimental [2] or bioinformatic analysis [3]. Even though polyP accumulates in some Crenarchaeotes, no archaeal PPK homolog has been found so far, suggesting a different enzyme involved in polyP synthesis in this phylum
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