Interaction of Candida albicans cell wall Als3 protein with Streptococcus gordonii SspB adhesin promotes development of mixed-species communities

School of Oral and Dental Sciences, University of Bristol, Bristol, United Kingdom.
Infection and immunity (Impact Factor: 4.16). 11/2010; 78(11):4644-52. DOI: 10.1128/IAI.00685-10
Source: PubMed

ABSTRACT Candida albicans colonizes human mucosa and prosthetic surfaces associated with artificial joints, catheters, and dentures. In the oral cavity, C. albicans coexists with numerous bacterial species, and evidence suggests that bacteria may modulate fungal growth and biofilm formation. Streptococcus gordonii is found on most oral cavity surfaces and interacts with C. albicans to promote hyphal and biofilm formation. In this study, we investigated the role of the hyphal-wall protein Als3p in interactions of C. albicans with S. gordonii. Utilizing an ALS3 deletion mutant strain, it was shown that cells were not affected in initial adherence to the salivary pellicle or in hyphal formation in the planktonic phase. However, the Als3(-) mutant was unable to form biofilms on the salivary pellicle or deposited S. gordonii DL1 wild-type cells, and after initial adherence, als3Δ/als3Δ (ΔALS3) cells became detached concomitant with hyphal formation. In coaggregation assays, S. gordonii cells attached to, and accumulated around, hyphae formed by C. albicans wild-type cells. However, streptococci failed to attach to hyphae produced by the ΔALS3 mutant. Saccharomyces cerevisiae S150-2B cells expressing Als3p, but not control cells, supported binding of S. gordonii DL1. However, S. gordonii Δ(sspA sspB) cells deficient in production of the surface protein adhesins SspA and SspB showed >50% reduced levels of binding to S. cerevisiae expressing Als3p. Lactococcus lactis cells expressing SspB bound avidly to S. cerevisiae expressing Als3p, but not to S150-2B wild-type cells. These results show that recognition of C. albicans by S. gordonii involves Als3 protein-SspB protein interaction, defining a novel mechanism in fungal-bacterial communication.

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    • "To identify the CWPs on C. albicans involved, Nobbs et al. screened a panel of C. albicans CWPs for adhesion to biotic and abiotic surfaces and bacteria including S. gordonii and found that Als3, Eap1, and Hwp1 were able to enhance binding to S. gordonii (Nobbs et al., 2010) with the most important role for Als3. Further evidence suggested that SspB is the main bacterial ligand for this receptor and that both Als3 and SspB have amyloid properties, providing a model of adherence between both proteins (Silverman et al., 2010). Another important bacterial pathogen is S. aureus, which is associated with severe disease and high mortality (Harriott & Noverr, 2009). "
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    ABSTRACT: A considerable number of infectious diseases involve multiple microbial species coexisting and interacting in a host. Only recently however the impact of these polymicrobial diseases has been appreciated and investigated. Often, the causative microbial species are embedded in an extracellular matrix forming biofilms, a form of existence that offers protection against chemotherapeutic agents and host immune defenses. Therefore, recent efforts have focused on developing novel therapeutic strategies targeting biofilm-associated polymicrobial infections, a task which has proved to be challenging. One promising approach to inhibit the development of such complex infections is to impede the interactions between the microbial species via inhibition of adhesion. To that end, studies have focused on identifying specific cell wall adhesins and receptors involved in the interactions between the various bacterial species and the most pathogenic human fungal species Candida albicans. This review highlights the important findings from these studies and describes the available tools and techniques that have provided insights into the role of secreted molecules orchestrating microbial interactions in biofilms. Specifically, we focus on the interactions that take place in oral biofilms and the implications of these interactions on oral health and therapeutic strategies. This article is protected by copyright. All rights reserved.
    Pathogens and Disease 12/2013; 70(3). DOI:10.1111/2049-632X.12123 · 2.55 Impact Factor
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    • "Especially the Als3 protein seems to play a vital role in adhesion, since its deletion strongly reduces adhesion to epithelial cells (Hoyer et al., 2008; Wächtler et al., 2012). In addition, this protein is also important for iron acquisition from ferritin (Almeida et al., 2008), formation of mixed-species biofilms (Silverman et al., 2010) and induction of endocytosis by host cells (Phan et al., 2007; Wächtler et al., 2012 and see also next section). As Als3 is hypha-associated (Argimon et al., 2007), it is expressed as the fungus forms filaments, for example upon physical contact with host cells, at body temperature and at ambient neutral pH. "
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    ABSTRACT: Candida albicans and C. glabrata are the two most common pathogenic yeasts of humans, yet they are phylogenetically, genetically, and phenotypically very different. In this review, we compare and contrast the strategies of C. albicans and C. glabrata to attach to and invade into the host, obtain nutrients, and evade the host immune response. Although their strategies share some basic concepts, they differ greatly in their outcome. While C. albicans follows an aggressive strategy to subvert the host response and to obtain nutrients for its survival, C. glabrata seems to have evolved a strategy which is based on stealth, evasion and persistence, without causing severe damage in murine models. However, both fungi are successful as commensals and as pathogens of humans. Understanding these strategies will help in finding novel ways to fight Candida, and fungal infections in general.
    Cellular Microbiology 12/2012; 15(5). DOI:10.1111/cmi.12091 · 4.82 Impact Factor
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    • "albicans is generally diploid) (Zhao et al., 2004). Als3p is hypha-specific (Murciano et al., 2012) and is in all probability involved in early establishment of biofilms in addition to interacting with oral streptococci (Silverman et al., 2010). "
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    ABSTRACT: Establishment of a community is considered to be essential for microbial growth and survival in the human oral cavity. Biofilm communities have increased resilience to physical forces, antimicrobial agents and nutritional variations. Specific cell-to-cell adherence processes, mediated by adhesin-receptor pairings on respective microbial surfaces, are able to direct community development. These interactions co-localize species in mutually beneficial relationships, such as streptococci, veillonellae, Porphyromonas gingivalis and Candida albicans. In transition from the planktonic mode of growth to a biofilm community, microorganisms undergo major transcriptional and proteomic changes. These occur in response to sensing of diffusible signals, such as autoinducer molecules, and to contact with host tissues or other microbial cells. Underpinning many of these processes are intracellular phosphorylation events that regulate a large number of microbial interactions relevant to community formation and development.
    11/2012; 28(2). DOI:10.1111/omi.12012
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