Abstract
BackgroundMembers of Rhizopus species are the most common cause of mucormycosis, a rare but often fatal fungal infection. Host induced pathogen apoptosis and pathogen induced host cell apoptosis are often involved in fungal infections. In many organisms, the release of mitochondrial cytochrome c can trigger apoptosis by activating caspase proteases, but the role of fungal cytochrome c in apoptosis remains unknown.ResultsDNA sequence encoding Rhizopus arrhizus cytochrome c was cloned and expressed in E. coli. Both native and recombinant cytochrome c were purified using ion exchange followed by gel filtration chromatography. The identities of purified proteins were confirmed by MALDI-MS and UV-Visible spectroscopy. For the first time, we demonstrated that Rhizopus arrhizus cytochrome c could activate human capspase-3 in HeLa cell extracts. We also found that Rhizopus arrhizus cytochrome c has redox potential, peroxidase activity, and spectral properties similar to human and horse cytochrome c proteins.ConclusionsRhizopus arrhizus cytochrome c can activate human caspase-3 in HeLa cell extracts and it possesses similar physical and spectral properties as human and horse cytochrome c. This protein was found to have a previously unknown potential to activate human caspase-3, an important step in the apoptosis cascade.Electronic supplementary materialThe online version of this article (doi:10.1186/s12858-015-0050-9) contains supplementary material, which is available to authorized users.
Highlights
Members of Rhizopus species are the most common cause of mucormycosis, a rare but often fatal fungal infection
The eluted cyt c produced one band, which had an apparent MW of ca. 14 kDa (Fig. 1c). Since this is the first report on purification of recombinant R. arrhizus cyt c, we compared our purification results with those reported by others using similar plasmids
A better understanding of the role of specific sequences in cyt c’s ability to induce apoptosis and its differences with mammalian cyt c could lead to the identification of methods for exclusive targeting of this fungal pathogen
Summary
Members of Rhizopus species are the most common cause of mucormycosis, a rare but often fatal fungal infection. Host induced pathogen apoptosis and pathogen induced host cell apoptosis are often involved in fungal infections. Mucormycosis are rare but often life-threatening infections seen in immunocompromised, diabetic, and organ transplant patients [1]. These infections are difficult to treat and with an increase in the number of diabetic patients and organ transplants, in the future such infections are likely to increase [1, 2]. In response to fungal infections, the oxidative burst by host immune cells could help in infection clearance by triggering apoptosis in the fungus [4, 5]. Pathogen-induced apoptosis in host immune cells could help the pathogen to establish the infection [6]. The nature of the role cyt c plays in apoptosis of filamentous fungi like R. arrhizus remains unknown
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