Crosslinks in the cell wall of budding yeast control morphogenesis at the mother–bud neck

Blánco, N.; Reidy, Michael; Arroyo, Javier; Cabib, Enrico

doi:10.1242/jcs.110460

Cited by 32 publications

(23 citation statements)

References 36 publications

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“…2B) shows the typical b-jelly roll arrangement that is common in the GH16 family [29][30][31]. A comparison of the model with the bacterial template indicates that there is an extra loop (residues [22][23][24][25][26][27][28][29][30][31][32][33][34][35] that is located in the active site and not present in the Crh1 model ( Fig. 2A).…”

Section: Resultsmentioning

confidence: 99%

“…We have previously demonstrated that both Crh1 and Crh2 are responsible for the cross‐linking between chitin and glucan at the yeast cell wall in vivo . Moreover, these cross‐links are essential for the control of yeast morphogenesis at the mother–bud neck . These enzymes act as transglycosylases incorporating β‐1,3‐linked, β‐1,6‐linked and chitooligosaccharides into the cell wall as chitin acceptors .…”

Section: Discussionmentioning

confidence: 99%

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Structural and functional analysis of yeast Crh1 and Crh2 transglycosylases

et al. 2015

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Covalent cross-links between chitin and glucan at the yeast cell wall are created by the transglycosylase activity of redundant proteins Crh1 and Crh2, with cleavage of b-1,4 linkages of the chitin backbone and transfer of the generated molecule containing newly created reducing end onto the glucan acceptor. A three-dimensional structure of Crh1 was generated by homology modeling based on the crystal structure of bacterial 1,3-1,4-b-D-glucanase, followed by site-directed mutagenesis to obtain molecular insights into how these enzymes achieve catalysis. The residues of both proteins that are involved in their catalytic and binding activities have been characterized by measuring the ability of yeast cells expressing different versions of these proteins to transglycosylate oligosaccharides derived from b-1,3-glucan, b-1,6-glucan and chitin to the chitin at the cell wall. Within the catalytic site, residues E134 and E138 of Crh1, as well as E166 and E170 of Crh2, corresponding to the nucleophile and general acid/base, and also the auxiliary D136 and D168 of Crh1 and Crh2, respectively, are shown to be essential for catalysis. Mutations of aromatic residues F152, Y160 and W219, located within the carbohydrate-binding cleft of the Crh1 model, also affect the transglycosylase activity. Unlike Crh1, Crh2 contains a putative carbohydrate-binding module (CBM18) of unknown function. Modeling and functional analysis of site-directed mutant residues of this CBM identified essential amino acids for protein folding and stability, as well as residues that tune the catalytic activity of Crh2.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Structural and functional analysis of yeast Crh1 and Crh2 transglycosylases

et al. 2015

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“…These modifications were observed along with a diminution of the ␤-1,3-glucan content and an increase in the chitin content. Studies by Cabib and coworkers have shown the importance of chitin and ␤-1,3-glucans during the cell division of yeasts (38)(39)(40). Their work focused on the remodeling of the cell wall during cell division, and particularly on the neck at the mother-bud interface.…”

Section: Discussionmentioning

confidence: 99%

Nanoscale Effects of Caspofungin against Two Yeast Species, Saccharomyces cerevisiae and Candida albicans

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Martin-Yken

et al. 2013

Antimicrob Agents Chemother

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Saccharomyces cerevisiae and Candida albicans are model yeasts for biotechnology and human health, respectively. We used atomic force microscopy (AFM) to explore the effects of caspofungin, an antifungal drug used in hospitals, on these two species. Our nanoscale investigation revealed similar, but also different, behaviors of the two yeasts in response to treatment with the drug. While administration of caspofungin induced deep cell wall remodeling in both yeast species, as evidenced by a dramatic increase in chitin and decrease in ␤-glucan content, changes in cell wall composition were more pronounced with C. albicans cells. Notably, the increase of chitin was proportional to the increase in the caspofungin dose. In addition, the Young modulus of the cell was three times lower for C. albicans cells than for S. cerevisiae cells and increased proportionally with the increase of chitin, suggesting differences in the molecular organization of the cell wall between the two yeast species. Also, at a low dose of caspofungin (i.e., 0.5؋ MIC), the cell surface of C. albicans exhibited a morphology that was reminiscent of cells expressing adhesion proteins. Interestingly, this morphology was lost at high doses of the drug (i.e., 4؋ MIC). However, the treatment of S. cerevisiae cells with high doses of caspofungin resulted in impairment of cytokinesis. Altogether, the use of AFM for investigating the effects of antifungal drugs is relevant in nanomedicine, as it should help in understanding their mechanisms of action on fungal cells, as well as unraveling unexpected effects on cell division and fungal adhesion.T he yeast cell wall is composed of 50 to 60% ␤-glucans (glucose residues attached by 1,3-␤-and 1,6-␤-linkages), 40 to 50% mannoproteins (highly glycosylated polypeptides), and 1 to 3% chitin (1, 2). It is an essential dynamic structure playing roles in maintaining cell shape and integrity, sensing the surrounding environment, and interacting with surfaces and other cells (3). The cell wall represents 15 to 25% of the cell dry mass, the chemical composition of which is well established. Saccharomyces cerevisiae, also called baker's yeast, is the best-characterized eukaryotic model for scientific and biomedical research. Although the chemical composition of the yeast cell wall is well known, its molecular ultrastructure (organization or assembly) has not been extensively studied at nanoscale (4, 5), although there are a few reports on the nanomechanical and adhesive properties of the yeast cell wall under native conditions or under stress conditions (6-8). As for Candida albicans, it is by far the most common human-pathogenic fungal species. It can cause a range of pathogenic effects, including painful superficial infections, severe surface infections, and lifethreatening bloodstream infections (9). It is a major cause of morbidity and mortality in immunocompromised patients as a result of AIDS, cancer chemotherapy, or organ transplantation (10).Given its medical relevance, C. albicans has been the subject of extens...

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“…The large diameter of the necks of these buds signifies that the size of the cytokinetic ring of septins and contractile proteins is not fixed, reminiscent of consequences of deletion of the bud neck kinase, Cla4, from haploid cells (59).…”

Section: Discussionmentioning

confidence: 99%

Sequential Logic of Polarity Determination during the Haploid-to-Diploid Transition in Saccharomyces cerevisiae

et al. 2014

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cIn many organisms, the geometry of encounter of haploid germ cells is arbitrary. In Saccharomyces cerevisiae, the resulting zygotes have been seen to bud asymmetrically in several directions as they produce diploid progeny. What mechanisms account for the choice of direction, and do the mechanisms directing polarity change over time? Distinct subgroups of cortical "landmark" proteins guide budding by haploid versus diploid cells, both of which require the Bud1/Rsr1 GTPase to link landmarks to actin. We observed that as mating pairs of haploid cells form zygotes, bud site specification progresses through three phases. The first phase follows disassembly and limited scattering of proteins that concentrated at the zone of cell contact, followed by their reassembly to produce a large medial bud. Bud1 is not required for medial placement of the initial bud. The second phase produces a contiguous bud(s) and depends on axial landmarks. As the titer of the Axl1 landmark diminishes, the third phase ultimately redirects budding toward terminal sites and is promoted by bipolar landmarks. Thus, following the initial random encounter that specifies medial budding, sequential spatial choices are orchestrated by the titer of a single cortical determinant that determines whether successive buds will be contiguous to their predecessors.

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Crosslinks in the cell wall of budding yeast control morphogenesis at the mother–bud neck

Cited by 32 publications

References 36 publications

Structural and functional analysis of yeast Crh1 and Crh2 transglycosylases

Structural and functional analysis of yeast Crh1 and Crh2 transglycosylases

Nanoscale Effects of Caspofungin against Two Yeast Species, Saccharomyces cerevisiae and Candida albicans

Sequential Logic of Polarity Determination during the Haploid-to-Diploid Transition in Saccharomyces cerevisiae

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