Lipase 8 Affects the Pathogenesis ofCandida albicans

Abstract

The production of lipases can affect microbial fitness and virulence. We examined the role of the lipase 8 (LIP8) gene in the virulence of Candida albicans by constructing ⌬lip8 strains by the URA-blaster disruption method. Reverse transcription-PCR experiments demonstrated the absence of LIP8 expression in the homozygous knockout mutants. Reconstituted strains and overexpression mutants were generated by introducing a LIP8 open reading frame under control of a constitutive actin promoter. Knockout mutants produced more mycelium, particularly at higher temperatures and pH >7. Diminished LIP8 expression resulted in reduced growth in lipid-containing media. Mutants deficient in the LIP8 gene were significantly less virulent in a murine intravenous infection model. The results clearly indicate that Lip8p is an important virulence factor of C. albicans.Lipases catalyze both the hydrolysis and synthesis of triacylglycerols (4). Many of these enzymes are characterized by stability at high temperatures and in organic solvents, high enantioselectivity, and resistance to proteolysis, which make them ideal candidates for diverse commercial applications. In addition to the industrial uses of lipases, there is an evolving literature on their role as important microbial virulence factors (3, 42). The putative roles of microbial extracellular lipases include digestion of lipids for nutrient acquisition, adhesion to host cells and host tissues, synergistic interactions with other enzymes, nonspecific hydrolysis due to additional phospholipolytic activities, initiation of inflammatory processes by affecting immune cells, and self-defense mediated by lysing competing microflora (37, 43). Extracellular lipases have been proposed to be potential virulence factors of bacterial pathogens, including Staphylococcus aureus (47), Staphylococcus epidermidis (24), Propionibacterium acnes (26), and Pseudomonas aeruginosa (18), as well as pathogenic fungi, such as Malassezia furfur (33), Hortaea werneckii (13), and Candida species (37,43).Candida albicans is recognized as the leading opportunistic pathogen involved in oral, vaginal, and systemic infections. It is the fourth most common cause of bloodstream infection in the United States and has a high attributable mortality rate (32). Besides yeast-to-hypha transition, adhesion factors, surface hydrophobicity, phenotypic switching, thigmotropism, and molecular mimicry (7), the secretion of hydrolytic enzymes like proteinases or lipases may also affect C. albicans virulence. Although the secretion of aspartic proteinases (Sap1p to Sap10p) has been shown to be a key virulence determinant of C. albicans (15,27,29,38,41,45), limited information is available about the involvement of lipases in Candida infection.Extracellular lipase activity of C. albicans was first described in 1965 (53), and the first lipase gene, LIP1, was identified in 1997 (11). Results of Southern blot analysis using LIP1 as a probe under low-stringency conditions suggested the existence of a larger lipase gene family. More...

In-vitro Inhibition of Biofilm Formation in Candida albicans and Candida tropicalis by Heat Stable Compounds in Culture Filtrate of Aspergillus flavus

“…Candida spp. produce several virulence factors like Secreted aspartyl proteases (SAP) and lipases among others that helps the pathogen establish infection in the susceptible host [20,8]. So there is an imminent need of developing new antifungal agents that would aim at inhibiting biofilm formation, one of the main pathogenic mechanism of Candida spp.…”

“…Organochlorine compounds like Aspirochlorine, derived from Aspergillus flavus have shown significant activity against Candida albicans [7]. Lipase enzyme production plays an important role in pathogenesis of invasive infection caused by Candida albicans and Candida tropicalis in addition to biofilm formation [8]. Keeping these points in mind, we aimed to study the effect of crude culture filtrate of Aspergillus flavus, both plain and unheated, on biofilm formation and lipase inhibition of Candida albicans and C. tropicalis.…”

Virulence Traits Contributing to Pathogenicity of Candida Species

“…Extracellular lipase production in C. albicans was first described by Werner (1965) [27]. C. albicans lipases are encoded by 10 genes (LIP1 to LIP10) [27]. Similar sequences are also identified in C. tropicalis.…”

“…This group of enzymes also alters host defense by lysing competing microflora. Extracellular lipase production in C. albicans was first described by Werner (1965) [27]. C. albicans lipases are encoded by 10 genes (LIP1 to LIP10) [27].…”

“…Lipases also nonspecifically initiate inflammatory processes by enhancing cell mediated immunity [27]. This group of enzymes also alters host defense by lysing competing microflora.…”