Functional amyloid in Pseudomonas

Abstract

SummaryAmyloids are highly abundant in many microbial biofilms and may play an important role in their architecture. Nevertheless, little is known of the amyloid proteins. We report the discovery of a novel functional amyloid expressed by a Pseudomonas strain of the P. fluorescens group. The amyloid protein was purified and the amyloid-like structure verified. Partial sequencing by MS/MS combined with full genomic sequencing of the Pseudomonas strain identified the gene coding for the major subunit of the amyloid fibril, termed fapC. FapC contains a thrice repeated motif that differs from those previously found in curli fimbrins and prion proteins. The lack of aromatic residues in the repeat shows that aromatic side chains are not needed for efficient amyloid formation. In contrast, glutamine and asparagine residues seem to play a major role in amyloid formation as these are highly conserved in curli, prion proteins and FapC. fapC is conserved in many Pseudomonas strains including the opportunistic pathogen P. aeruginosa and is situated in a conserved operon containing six genes, of which one encodes a fapC homologue. Heterologous expression of the fapA-F operon in Escherichia coli BL21(DE3) resulted in a highly aggregative phenotype, showing that the operon is involved in biofilm formation.

Self-assembly of functional, amphipathic amyloid monolayers by the fungal hydrophobin EAS

“…7D). Asparagine and glutamine ladders are believed to add extra stability to certain amyloids, in particular to some other functional amyloids (29,30). They are found in parallel β-helix proteins (31) and in the β-solenoid structure of the fungal prion amyloid formed by Het-S (32).…”

Programmable biofilm-based materials from engineered curli nanofibres

“…In harsher environments, the highly robust amyloid matrix, once assembled, could persist beyond the lifetime of the cellular components as an acellular structure without the need for maintenance. In principle, our approach can be used to introduce new function to many other microbial biofilms with analogous functional amyloids (for example, Salmonella 46 , Pseudomonas 47 , Bacillus 48 spp.) to capitalize on the particular features of each wild-type strain.…”

Cyclin-dependent Kinase 5 Phosphorylation of Familial Prion Protein Mutants Exacerbates Conversion into Amyloid Structure

“…1B), confirming phosphorylation of PrP WT at serine 43 (Ser 43 ) by Cdk5. Before evaluating Cdk5-mediated phosphorylation of the familial PrP mutants, the time of maximal phosphorylation of PrP was determined to plateau at around 4 h (Fig.…”

“…Together, these results indicate that phosphorylation at Ser 43 amplifies the nucleation-dependent polymerization of Y145X and Q160X PrP into Thioflavin T-positive and PK-resistant fibrillar amyloid.…”

“…PrP is phosphorylated by various kinases, including Fyn and casein kinase II (14). PrP is also phosphorylated at Ser 43 (pPrP S43 ) by neuronal cyclin-dependent kinase 5 (Cdk5), and pPrP S43 forms proteinase K-resistant aggregates and accumulates in scrapie-infected mouse brains (15). Cdk5 levels are increased in PrP SC -infected brains (16), and the p25/p35 activators of Cdk5 and Cdk5 increase with age (17).…”