Alternative oxidase promotes high iron tolerance in .

The yeast exhibits metabolic flexibility for adaptability to host niches with varying availability of nutrients including essential metals like iron. For example, blood is iron deplete, while the oral cavity and the intestinal lumen are considered iron replete. We show here that can tolerate very high levels of environmental iron, despite an increase in high iron-induced reactive oxygen species (ROS) that it mitigates with the help of a unique oxidase, known as alternative oxidase (AOX).

Prolonged mask wearing does not alter the oral microbiome, salivary flow rate or gingival health status - A pilot study.

The COVID-19 pandemic has resulted in the widespread use of N95 respirators and surgical masks, with anecdotal reports among healthcare providers and the public of xerostomia, halitosis, and gingivitis, a consortium of symptoms colloquially termed "mask mouth". However, this has not been scientifically verified. The aim of this study was to assess changes in salivary flow rate, gingival health status and oral microbiome associated with prolonged mask use.

High iron-mediated increased oral fungal burden, oral-to-gut transmission, and changes to pathogenicity of in oropharyngeal candidiasis.

Background: Iron affects the diversity of the oral microbial landscape. Laboratory-strain CAI4 of that causes oropharyngeal candidiasis (OPC) exhibits iron-induced changes to the cell wall, impacting phagocytosis (by macrophages) and susceptibility of fungal cells to cell wall-perturbing antifungals, .

Aim: To understand the effect of iron on the CAI4-strain, wild type (WT) SC5314-strain, and oral isolates of .

Antifungal properties of (2S, 4R)-Ketoconazole sulfonamide analogs.

Invasive candidiasis remains a significant health concern, as it is associated with a high mortality risk. In addition, the risk of infection is significantly elevated in immunocompromised patients such as those with HIV, cancer, or those taking imcmunosuppressive drugs as a result of organ transplantation. The majority of these cases are caused by , and is the second most common cause.

Antifungal Effect of Piezoelectric Charges on PMMA Dentures.

Candida-associated denture stomatitis is a recurring disease affecting up to 67% of denture wearers. Poly(methyl methacrylate) (PMMA) remains the main material employed in the fabrication of dentures due to its desirable physical, mechanical, and aesthetic properties. However, the improvement of its antimicrobial properties remains a challenge.

Screening of Health-Associated Oral Bacteria for Anticancer Properties .

While extensive literature exists about the role of oral bacterial pathogens like and in oral squamous cell carcinoma (OSCC), the role of health-associated species has been largely unexplored. In this study, we assessed the effect of , and on proliferation and expression of marker genes (IL-6, TNF-α, MMP3, CD36, CCD1, and NANOG) in OSCC cell lines CAL27, SCC25, and SCC4. was included as a pathogenic control.

Supragingival mycobiome and inter-kingdom interactions in dental caries.

: Recent studies have reveled the presence of a complex fungal community (mycobiome) in the oral cavity. However, the role of oral mycobiome in dental caries and its interaction with caries-associated bacteria is not yet clear. : Whole-mouth supragingival plaque samples from 30 children (6-10 years old) with no caries, early caries, or advanced caries were sequenced for internal transcribed spacer 2 (ITS-2).

Iron Chelator Deferasirox Reduces Invasion of Oral Epithelial Cells and Infection Levels in Murine Oropharyngeal Candidiasis.

, the causative agent of mucosal infections, including oropharyngeal candidiasis (OPC), as well as bloodstream infections, is becoming increasingly resistant to existing treatment options. In the absence of novel drug candidates, drug repurposing aimed at using existing drugs to treat off-label diseases is a promising strategy. requires environmental iron for survival and virulence, while host nutritional immunity deploys iron-binding proteins to sequester iron and reduce fungal growth.

Metagenome sequencing-based strain-level and functional characterization of supragingival microbiome associated with dental caries in children.

Studies of the microbiome associated with dental caries have largely relied on 16S rRNA sequence analysis, which is associated with PCR biases, low taxonomic resolution, and inability to accurately study functions. Here, we employed whole metagenome shotgun sequencing, coupled with high-resolution analysis algorithm, to analyze supragingival microbiomes from 30 children with or without dental caries. A total of 726 bacterial strains belonging to 406 species, in addition to 34 bacteriophages were identified.

Salivary metals, age, and gender correlate with cultivable oral carriage levels.

: Little is known about the normal range of metal levels in unstimulated saliva, nor whether these might impact carriage in healthy individuals. Both are important in determining which populations are at risk for candidiasis, as the availability of metal ions can influence the growth and pathogenesis of . : We quantified salivary metals of healthy individuals to determine the correlation with oral colonization.

Structural Characterization of Histatin 5-Spermidine Conjugates: A Combined Experimental and Theoretical Study.

Histatin 5 (Hst5) is a naturally occurring antimicrobial peptide that acts as the first line of defense against oral candidiasis. It has been shown that conjugation of the active Hst5 fragment, Hst5, and the polyamine spermidine (Spd) improves the candidacidal effect. Knowledge about the structure of these conjugates is, however, very limited.

Human Salivary Protein Histatin 5 Has Potent Bactericidal Activity against ESKAPE Pathogens.

ESKAPE (, , , , , and species) pathogens have characteristic multiple-drug resistance and cause an increasing number of nosocomial infections worldwide. Peptide-based therapeutics to treat ESKAPE infections might be an alternative to conventional antibiotics. Histatin 5 (Hst 5) is a salivary cationic histidine-rich peptide produced only in humans and higher primates.

Candida albicans Shed Msb2 and Host Mucins Affect the Candidacidal Activity of Salivary Hst 5.

Salivary Histatin 5 (Hst 5) is an antimicrobial peptide that exhibits potent antifungal activity towards Candida albicans, the causative agent of oral candidiasis. However, it exhibits limited activity in vivo, largely due to inactivation by salivary components of both host and pathogen origin. Proteins secreted by C.

Candida albicans Cek1 mitogen-activated protein kinase signaling enhances fungicidal activity of salivary histatin 5.

Candida albicans is a major etiological organism for oropharyngeal candidiasis (OPC), while salivary histatin 5 (Hst 5) is a human fungicidal protein that protects the oral cavity from OPC. C. albicans senses its environment by mitogen-activated protein kinase (MAPK) activation that can also modulate the activity of some antifungal drugs, including Hst 5.

How does it kill?: understanding the candidacidal mechanism of salivary histatin 5.

Histatins are salivary cationic peptides that provide the first line of defense against oral candidiasis caused by Candida albicans. This minireview presents a critical evaluation of our knowledge of the candidacidal mechanism of histatin 5 (Hst 5). Hst 5 is the most potent among all histatin family members with regard to its antifungal activity.

Iron-responsive chromatin remodelling and MAPK signalling enhance adhesion in Candida albicans.

Recent cumulative data show that various transcription factors are recruited to the chromatin in an iron-responsive manner to affect diverse cellular functions in the pathogenic fungus Candida albicans. Here we identified groups of iron-responsive genes in C. albicans by chromatin remodelling analysis at gene promoters, using micrococcal nuclease (MNase) digestion followed by deep sequencing.

Histatin 5-spermidine conjugates have enhanced fungicidal activity and efficacy as a topical therapeutic for oral candidiasis.

Oropharyngeal candidiasis (OPC) is caused by the opportunistic fungi Candida albicans and is prevalent in immunocompromised patients, individuals with dry mouth, or patients with prolonged antibiotic therapies that reduce oral commensal bacteria. Human salivary histatins, including histatin 5 (Hst 5), are small cationic proteins that are the major source of fungicidal activity of saliva. However, Hsts are rapidly degraded in vivo, limiting their usefulness as therapeutic agents despite their lack of toxicity.

Histatin 5 resistance of Candida glabrata can be reversed by insertion of Candida albicans polyamine transporter-encoding genes DUR3 and DUR31.

Candida albicans and Candida glabrata are predominant fungi associated with oral candidiasis. Histatin 5 (Hst 5) is a small cationic human salivary peptide with high fungicidal activity against C. albicans, however many strains of C.

Candida albicans flu1-mediated efflux of salivary histatin 5 reduces its cytosolic concentration and fungicidal activity.

Histatin 5 (Hst 5) is a salivary human antimicrobial peptide that is toxic to the opportunistic yeast Candida albicans. Fungicidal activity of Hst 5 requires intracellular translocation and accumulation to a threshold concentration for it to disrupt cellular processes. Previously, we observed that total cytosolic levels of Hst 5 were gradually reduced from intact cells, suggesting that C.

Secreted aspartic protease cleavage of Candida albicans Msb2 activates Cek1 MAPK signaling affecting biofilm formation and oropharyngeal candidiasis.

Perception of external stimuli and generation of an appropriate response are crucial for host colonization by pathogens. In pathogenic fungi, mitogen activated protein kinase (MAPK) pathways regulate dimorphism, biofilm/mat formation, and virulence. Signaling mucins, characterized by a heavily glycosylated extracellular domain, a transmembrane domain, and a small cytoplasmic domain, are known to regulate various signaling pathways.

Control of bacterial iron homeostasis by manganese.

Perception and response to nutritional iron availability by bacteria are essential to control cellular iron homeostasis. The Irr protein from Bradyrhizobium japonicum senses iron through the status of heme biosynthesis to globally regulate iron-dependent gene expression. Heme binds directly to Irr to trigger its degradation.

Positive control of ferric siderophore receptor gene expression by the Irr protein in Bradyrhizobium japonicum.

Ferric siderophore receptors are components of high-affinity iron-chelate transport systems in gram-negative bacteria. The genes encoding these receptors are generally regulated by repression. Here, we show that the ferrichrome receptor gene bll4920 and four additional putative ferric siderophore receptor genes in Bradyrhizobium japonicum are positively controlled by the regulatory protein Irr, as observed by the low level of mRNA transcripts in an irr mutant in iron-limited cells.

Heme-dependent metalloregulation by the iron response regulator (Irr) protein in Rhizobium and other Alpha-proteobacteria.

Perception and response to nutritional iron by bacteria is essential for viability, and for the ability to adapt to the environment. The iron response regulator (Irr) is part of a novel regulatory scheme employed by Rhizobium and other Alpha-Proteobacteria to control iron-dependent gene expression. Bradyrhizobium japonicum senses iron through the status of heme biosynthesis to regulate gene expression, thus it responds to an iron-dependent process rather than to iron directly.

The hmuQ and hmuD genes from Bradyrhizobium japonicum encode heme-degrading enzymes.

Utilization of heme by bacteria as a nutritional iron source involves the transport of exogenous heme, followed by cleavage of the heme macrocycle to release iron. Bradyrhizobium japonicum can use heme as an iron source, but no heme-degrading oxygenase has been described. Here, bioinformatics analyses of the B.