Analysis of the surface proteins of Acidithiobacillus ferrooxidans strain SP5/1 and the new, pyrite-oxidizing Acidithiobacillus isolate HV2/2, and their possible involvement in pyrite oxidation

Abstract

Two strains of rod-shaped, pyrite-oxidizing acidithiobacilli, their cell envelope structure and their interaction with pyrite were investigated in this study. Cells of both strains, Acidithiobacillus ferrooxidans strain SP5/1 and the moderately thermophilic Acidithiobacillus sp. strain HV2/2, were similar in size, with slight variations in length and diameter. Two kinds of cell appendages were observed: flagella and pili. Besides a typical Gram-negative cell architecture with inner and outer membrane, enclosing a periplasm, both strains were covered by a hitherto undescribed, regularly arranged 2-D protein crystal with p2-symmetry. In A. ferrooxidans, this protein forms a stripe-like structure on the surface. A similar surface pattern with almost identical lattice vectors was also seen on the cells of strain HV2/2. For the surface layer of both bacteria, a direct contact to pyrite crystals was observed in ultrathin sections, indicating that the S-layer is involved in maintaining this contact site. Observations on an S-layer-deficient strain show, however, that cell adhesion does not strictly depend on the presence of the S-layer and that this surface protein has an influence on cell shape. Furthermore, the presented data suggest the ability of the S-layer protein to complex Fe3+ ions, suggesting a role in the physiology of the microorganisms.

Nitrososphaera viennensis gen. nov., sp. nov., an aerobic and mesophilic, ammonia-oxidizing archaeon from soil and a member of the archaeal phylum Thaumarchaeota

“…Up to now, p3-symmetry was thought to be unique to the order Sulfolobales , given that all investigated species from this group had this symmetry and a consistent lattice value (Baumeister & Lembcke, 1992; Deatherage et al , 1983; Grogan, 1996; Klingl et al , 2013; König et al , 2007; Lembcke et al , 1991, 1993; Prüschenk & Baumeister, 1987; Prüschenk et al , 1987; Taylor et al , 1982; Veith et al , 2009). Thus, the occurrence of p3-symmetry in the thaumarchaeote EN76 T excludes this characteristic as a taxonomic marker for the order Sulfolobales (Klingl et al , 2011; König et al , 2007). …”

A New Addition to the Cell Plan of Anammox Bacteria: "Candidatus Kuenenia stuttgartiensis" Has a Protein Surface Layer as the Outermost Layer of the Cell

“…The intense signal in the PAS staining indicated that the Kustd1514 protein is highly glycosylated, which is a common feature of several S-layer proteins (49). In bacteria, O-glycosylation seems most abundant, although some N-glycosylated (S-layer) proteins have also been described (28,58). The Kustd1514 protein contains both potential O-and N-glycosylation sites, as found by a manual search of the protein sequence for strict "consensus" sequences and by using the GlycoPP prediction server (59).…”

“…Kuenenia stuttgartiensis" cells is thus invested in synthesizing S-layer proteins, and it is therefore obvious to raise the question of which function the Slayer has for this anammox bacterium. Multiple functions for Slayers in prokaryotes have been proposed (65), including protection against predation (68,69), adhesion of cell-associated exoenzymes (70), osmoprotection (71), and maintaining cell shape and integrity (58,64). The latter function seems especially interesting in the case of anammox bacteria, since they are proposed to lack peptidoglycan and might therefore be in need of a structure that maintains cell shape and integrity.…”

“…In the case of Archaea, which also lack peptidoglycan (23,72), S-layers are indeed often assumed to have a function in maintaining cellular integrity, which is also substantiated by the fact that S-layer-deficient mutants in Archaea have not been found (64). Loss of S-layers in laboratory strains is a common feature of Bacteria, which probably occurs when the cells do not need their S-layers under culturing conditions, in which case S-layer-deficient mutants might outgrow S-layer-containing cells (58,73). If the S-layer indeed plays a role in maintaining the integrity of the cell, this could also explain why the S-layers have not been lost in our "Ca.…”

In vitro assembly and activity of an archaeal CRISPR-Cas type I-A Cascade interference complex

“…After blotting on a filter paper, the samples were washed twice on a drop of double distilled water and blotted each time. Finally, the proteins were negatively stained with 2% (w/v) uranyl acetate for 20 s, blotted again on filter paper and left for air drying (52,53). Electron microscopy and further analysis was carried out on a JEOL JEM-2100 transmission electron microscope (JEOL, Tokyo, Japan) operated at 120 kV.…”