Proteomic and metabolic characterization of a Candida albicans mutant resistant to the antimicrobial peptide MUC7 12-mer

Department of Oral Biology, University at Buffalo, the State University of New York, Buffalo, NY 14214, USA.
FEMS Immunology & Medical Microbiology (Impact Factor: 2.55). 09/2008; 54(1):80-91. DOI: 10.1111/j.1574-695X.2008.00450.x
Source: PubMed

ABSTRACT MUC7 12-mer is a cationic peptide derived from the N-terminal portion of human mucin MUC7, exhibiting potent antibacterial and antifungal properties. To advance our knowledge regarding the mechanisms of action of MUC7 peptide against an opportunistic fungal pathogen Candida albicans, we sought to develop and characterize mutant(s) resistant to this peptide. One of the selected mutants, designated #37, was much less susceptible to the MUC7 12-mer in a killing assay than the parental strain (ED(50)>40 vs. c. 6 microM, respectively). Difference gel electrophoresis (DIGE) analysis of the mutant revealed elevation of several glycolytic enzymes. The mutant also exhibited lowered ATP contents along with a relatively lower rate of oxygen consumption, as well as inability to grow on nonfermentable carbon sources. These properties are likely to be associated with changes in metabolic regulation, rather than lack of functional mitochondria, as determined by rhodamine 123 staining. Analysis of interaction between fluorescently labeled peptide and cells of both strains revealed that resistance of the mutant #37 is associated with changes in the process of transition between surface-bound state of the peptide to its internalization marking cell death.

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    • "The authors speculated that the impaired mitochondrial respiration leads to a decrease of the endogenous ROS level and as a result, to higher drug resistance. Comparable changes in the primary metabolism were also observed in a C. albicans mutant resistance to the human antimicrobial peptide MUC7 12-mer (Lis and Bobek, 2008). The application of fluconazole combined with the alkaloid berberine exerted a synergistic action against clinical, fluconazole-resistant C. albicans strains (Xu et al., 2009). "
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    • "Our earlier results have shown that MUC7 12-mer binds to the surface of C. albicans cells where it accumulates and then, in a concentration-dependent, all-or-none manner breaks membrane integrity leading to an influx of peptide molecules and immediate cell death (Lis and Bobek 2008). One can envision a scenario where the peptide interacting with the surface of plasma membrane imposes a stress perceived by the cell as similar to other environmental cues triggering calcium response. "
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    • "Although not widely used, proteomic methodologies contribute towards determining antimicrobial resistance mechanism(s) and other cell metabolic alterations through the capacity to analyze overall changes in bacteria (Cash, 2000). The pattern of protein species related to antimicrobial resistance has been researched in a variety of microorganisms and with different antimicrobial agents (Andrade et al., 2008; Bore et al., 2007; Cash et al., 1999; Coldham and Woodward, 2004; Diniz et al., 2004; Lis and Bobek, 2008; Mcatee et al., 2001; Pieper et al., 2006; Xu et al., 2006; Yoo et al., 2007). "
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