Cell Adhesion Proteins in the Nonvertebrate Eukaryotes

Lipke, Peter N.

doi:10.1007/978-3-642-80106-8_7

Cited by 13 publications

(8 citation statements)

References 170 publications

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“…There has been little work on the binding characteristics of microbial cell adhesion proteins, which can function under a variety of conditions not encountered in cell adhesion systems of multicellular organisms (28). Sexual cell adhesion in the yeast Saccharomyces cerevisiae is mediated through two interacting cell wall glycoproteins, a-agglutinin and ␣-agglutinin, which are expressed on haploid a and ␣ cells, respectively (29,41).…”

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confidence: 99%

Interaction of α-Agglutinin and a -Agglutinin, Saccharomyces cerevisiae Sexual Cell Adhesion Molecules

et al. 2001

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␣-Agglutinin and a-agglutinin are complementary cell adhesion glycoproteins active during mating in the yeast Saccharomyces cerevisiae. They bind with high affinity and high specificity: cells of opposite mating types are irreversibly bound by a few pairs of agglutinins. Equilibrium and surface plasmon resonance kinetic analyses showed that the purified binding region of ␣-agglutinin interacted similarly with purified a-agglutinin and with a-agglutinin expressed on cell surfaces. At 20°C, the K D for the interaction was 2 ؋ 10 ؊9 to 5 ؋ 10 ؊9M. This high affinity was a result of a very low dissociation rate (Ϸ 2.6 ؋ 10 ؊4 s ؊1 ) coupled with a low association rate ‫؍(‬ 5 ؋ 10 4 M ؊1 s ؊1 ). Circular-dichroism spectroscopy showed that binding of the proteins was accompanied by measurable changes in secondary structure. Furthermore, when binding was assessed at 10°C, the association kinetics were sigmoidal, with a very low initial rate. An induced-fit model of binding with substantial apposition of hydrophobic surfaces on the two ligands can explain the observed affinity, kinetics, and specificity and the conformational effects of the binding reaction.

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confidence: 99%

Interaction of α-Agglutinin and a -Agglutinin, Saccharomyces cerevisiae Sexual Cell Adhesion Molecules

et al. 2001

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“…However, in few cases has the functionality of multiple adhesion domains aside from the most N-terminal repeat of each adhesin been directly assessed. Studies to date have demonstrated distinct adhesion functions associated with the Aga1p-R1 domain, which is a common theme among fungal adhesins, typically bearing an N-terminal adhesion domain (Lipke 1996;Frieman et al 2002;Sundstrom 2002;Verstrepen et al 2004). We have been unable to find evidence for any direct adhesion functionality for the R2 domain of Aga1p in either our previous studies of its agglutination activity or in its ability to support the essential mating-specific function of the adhesins we describe here (Shen et al 2001;G.…”

Section: Discussionmentioning

confidence: 55%

“…Such a two-stage model of adhesion is also attractive as such interactions have been reported or predicted to char-acterize mating systems of other unicellular eukaryotes and, as will be discussed below, fungal pathogen-host interactions. In the mating process of the green alga Chlamydomonas, two-stage adhesin interactions have also been reported, where an initial contact is mediated through peripheral adhesin molecules and later on, a more intimate contact mediated through specific adhesion of membranes (Lipke 1996). In the mating processes of other unicellular eukaryotes such as the protist Tetrahymena thermophila, adhesion also proceeds by multiple contact-mediated interactions (Brown et al 1993).…”

Section: Discussionmentioning

confidence: 99%

“…The functions of these domains may be divided into two major categories: domains dedicated to adhesion interactions that are either protein-protein, lectin or transglutaminase mediated in nature, and domains whose repetition serves to increase the distance between the C-terminal GPI-associated plasma membrane and cell wall anchoring domain and the typically N-terminally distributed adhesion-mediating domains (Lipke 1996;Guo et al 2000;Frieman et al 2002;Huang et al 2003;Verstrepen et al 2004Verstrepen et al , 2005Kaur et al 2005;Dranginis et al 2007). Although most GPI-anchored adhesins contain both such types of domains, assigning individual domains to either of these categories may not be done exclusively in all cases, since recent work suggests that some repeated domains may influence not only overall size, but also aspects such as the hydrophobicity of adhesin proteins and therefore the cell surface when expressed in sufficient quantity (Verstrepen et al 2004;Fidalgo et al 2006;Ishigami et al 2006;Dranginis et al 2007).…”

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confidence: 99%

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Conserved WCPL and CX4C Domains Mediate Several Mating Adhesin Interactions inSaccharomyces cerevisiae

2009

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Several adhesins are induced by pheromones during mating in Saccharomyces cerevisiae, including Aga1p, Aga2p, Sag1p (Aga1p), and Fig2p. These four proteins all participate in or influence a well-studied agglutinin interaction mediated by Aga1p-Aga2p complexes and Sag1p; however, they also play redundant and essential roles in mating via an unknown mechanism. Aga1p and Fig2p both contain repeated, conserved WCPL and CX 4 C domains. This study was directed toward understanding the mechanism underlying the collective requirement of agglutinins and Fig2p for mating. Apart from the well-known agglutinin interaction between Aga2p and Sag1p, three more pairs of interactions in cells of opposite mating type were revealed by this study, including bilateral heterotypic interactions between Aga1p and Fig2p and a homotypic interaction between Fig2p and Fig2p. These four pairs of adhesin interactions are collectively required for maximum mating efficiency and normal zygote morphogenesis. GPI-less, epitope-tagged forms of Aga1p and Fig2p can be co-immunoprecipitated from the culture medium of mating cells in a manner dependent on the WCPL and CX 4 C domains in the R1 repeat of Aga1p. Using site-directed mutagenesis, the conserved residues in Aga1p that interact with Fig2p were identified. Aga1p is involved in two distinct adhesive functions that are independent of each other, which raises the possibility for combinatorial interactions of this protein with its different adhesion receptors, Sag1 and Fig2p, a property of many higher eukaryotic adhesins.

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“…Metazoan cell adhesion molecules have some domains homologous to fungal adhesins, and they contain predicted amyloid-forming sequences, including some that are rich in Ile, Val, and Thr [39, 69]. However, we have no experimental evidence to back up these bioinformatic inferences.…”

Section: Some Questions Not Yet Answeredmentioning

confidence: 99%

Between Amyloids and Aggregation Lies a Connection with Strength and Adhesion

Lipke

Ramsook

Garcia-Sherman

et al. 2014

New Journal of Science

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We tell of a journey that led to discovery of amyloids formed by yeast cell adhesins and their importance in biofilms and host immunity. We begin with the identification of the adhesin functional amyloid-forming sequences that mediate fiber formation in vitro. Atomic force microscopy and confocal microscopy show 2-dimensional amyloid “nanodomains” on the surface of cells that are activated for adhesion. These nanodomains are arrays of adhesin molecules that bind multivalent ligands with high avidity. Nanodomains form when adhesin molecules are stretched in the AFM or under laminar flow. Treatment with antiamyloid perturbants or mutation of the amyloid sequence prevents adhesion nanodomain formation and activation. We are now discovering biological consequences. Adhesin nanodomains promote formation and maintenance of biofilms, which are microbial communities. Also, in abscesses within candidiasis patients, we find adhesin amyloids on the surface of the fungi. In both human infection and a Caenorhabditis elegans infection model, the presence of fungal surface amyloids elicits anti-inflammatory responses. Thus, this is a story of how fungal adhesins respond to extension forces through formation of cell surface amyloid nanodomains, with key consequences for biofilm formation and host responses.

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Cell Adhesion Proteins in the Nonvertebrate Eukaryotes

Cited by 13 publications

References 170 publications

Interaction of α-Agglutinin and a -Agglutinin, Saccharomyces cerevisiae Sexual Cell Adhesion Molecules

Interaction of α-Agglutinin and a -Agglutinin, Saccharomyces cerevisiae Sexual Cell Adhesion Molecules

Conserved WCPL and CX4C Domains Mediate Several Mating Adhesin Interactions inSaccharomyces cerevisiae

Between Amyloids and Aggregation Lies a Connection with Strength and Adhesion

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