title: Yeast cell adhesion molecules have functional amyloid-forming sequences.
abstract: The occurrence of highly conserved amyloid-forming sequences in Candida albicans Als proteins (H. N. Otoo et al., Eukaryot. Cell 7:776-782, 2008) led us to search for similar sequences in other adhesins from C. albicans and Saccharomyces cerevisiae. The beta-aggregation predictor TANGO found highly beta-aggregation-prone sequences in almost all yeast adhesins. These sequences had an unusual amino acid composition: 77% of their residues were beta-branched aliphatic amino acids Ile, Thr, and Val, which is more than 4-fold greater than their prevalence in the S. cerevisiae proteome. High beta-aggregation potential peptides from S. cerevisiae Flo1p and C. albicans Eap1p rapidly formed insoluble amyloids, as determined by Congo red absorbance, thioflavin T fluorescence, and fiber morphology. As examples of the amyloid-forming ability of the native proteins, soluble glycosylphosphatidylinositol (GPI)-less fragments of C. albicans Als5p and S. cerevisiae Muc1p also formed amyloids within a few days under native conditions at nM concentrations. There was also evidence of amyloid formation in vivo: the surfaces of cells expressing wall-bound Als1p, Als5p, Muc1p, or Flo1p were birefringent and bound the fluorescent amyloid-reporting dye thioflavin T. Both of these properties increased upon aggregation of the cells. In addition, amyloid binding dyes strongly inhibited aggregation and flocculation. The results imply that amyloid formation is an intrinsic property of yeast cell adhesion proteins from many gene families and that amyloid formation is an important component of cellular aggregation mediated by these proteins.
authors.affiliation: Department of Biology, Brooklyn College, Brooklyn, NY 11210, USA.
authors.forename: Caleen B
authors.initials: CB
authors.lastname: Ramsook
authors.forename: Cho
authors.initials: C
authors.lastname: Tan
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Garcia
authors.forename: Raymond
authors.initials: R
authors.lastname: Fung
authors.forename: Gregory
authors.initials: G
authors.lastname: Soybelman
authors.forename: Ryan
authors.initials: R
authors.lastname: Henry
authors.forename: Anna
authors.initials: A
authors.lastname: Litewka
authors.forename: Shanique
authors.initials: S
authors.lastname: O'Meally
authors.forename: Henry N
authors.initials: HN
authors.lastname: Otoo
authors.forename: Roy A
authors.initials: RA
authors.lastname: Khalaf
authors.forename: Anne M
authors.initials: AM
authors.lastname: Dranginis
authors.forename: Nand K
authors.initials: NK
authors.lastname: Gaur
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Klotz
authors.forename: Jason M
authors.initials: JM
authors.lastname: Rauceo
authors.forename: Chong K
authors.initials: CK
authors.lastname: Jue
authors.forename: Peter N
authors.initials: PN
authors.lastname: Lipke
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism*; D052160:Benzothiazoles; D001718:Birefringence; D002118:Calcium / Q000494:pharmacology; D002176:Candida albicans / Q000166:cytology / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D002942:Circular Dichroism; D003224:Congo Red / Q000737:chemistry / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D037241:Mannose-Binding Lectins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008859:Microscopy, Polarization; D008958:Models, Molecular; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000235:genetics / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013844:Thiazoles / Q000737:chemistry / Q000494:pharmacology; D014162:Transfection; D015003:Yeasts / Q000166:cytology / Q000502:physiology*
chemical_list: C109455:ALA1 protein, Candida albicans; C093538:ALS1 protein, Candida albicans; D000682:Amyloid; D052160:Benzothiazoles; D015815:Cell Adhesion Molecules; C087578:FLO1 protein, S cerevisiae; C110690:FLO11 protein, S cerevisiae; D005656:Fungal Proteins; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D010448:Peptide Initiation Factors; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D013844:Thiazoles; C410795:eIF4E-associated protein Eap1; C009462:thioflavin T; D003224:Congo Red; D002118:Calcium