title: Functional amyloid in Pseudomonas.
abstract: Amyloids 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.
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Morten S
authors.initials: MS
authors.lastname: Dueholm
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Steen V
authors.initials: SV
authors.lastname: Petersen
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Sønderkær
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Larsen
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Gunna
authors.initials: G
authors.lastname: Christiansen
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Kim L
authors.initials: KL
authors.lastname: Hein
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Enghild
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Jeppe L
authors.initials: JL
authors.lastname: Nielsen
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Kåre L
authors.initials: KL
authors.lastname: Nielsen
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Per H
authors.initials: PH
authors.lastname: Nielsen
authors.affiliation: Centre for Insoluble Protein Structures, Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, DenmarkDepartment of Biotechnology, Chemistry, and Environmental Engineering, Aalborg University, 9000 Aalborg, DenmarkDepartments of Medical BiochemistryMedical MicrobiologyMolecular Biology, University of Aarhus (iNANO), 8000 Aarhus C, Denmark.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Otzen
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D023281:Genomics; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009876:Operon; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D000682:Amyloid