title: Candida albicans Rim13p, a protease required for Rim101p processing at acidic and alkaline pHs.
abstract: Candida albicans is an important commensal of mucosal surfaces that is also an opportunistic pathogen. This organism colonizes a wide range of host sites that differ in pH; thus, it must respond appropriately to this environmental stress to survive. The ability to respond to neutral-to-alkaline pHs is governed in part by the RIM101 signal transduction pathway. Here we describe the analysis of C. albicans Rim13p, a homolog of the Rim13p/PalB calpain-like protease member of the RIM101/pacC pathway from Saccharomyces cerevisiae and Aspergillus nidulans, respectively. RIM13, like other members of the RIM101 pathway, is required for alkaline pH-induced filamentation and growth under extreme alkaline conditions. Further, our studies suggest that the RIM101 pathway promotes pH-independent responses, including resistance to high concentrations of lithium and to the drug hygromycin B. RIM13 encodes a calpain-like protease, and we found that Rim101p undergoes a Rim13p-dependent C-terminal proteolytic processing event at neutral-to-alkaline pHs, similar to that reported for S. cerevisiae Rim101p and A. nidulans PacC. However, we present evidence that suggests that C. albicans Rim101p undergoes a novel processing event at acidic pHs that has not been reported in either S. cerevisiae or A. nidulans. Thus, our results provide a framework to understand how the C. albicans Rim101p processing pathway promotes alkaline pH-independent processes.
authors.affiliation: Department of Microbiology, University of Minnesota, Minneapolis MN 55455, USA.
authors.forename: Mingchun
authors.initials: M
authors.lastname: Li
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Martin
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Bruno
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Mitchell
authors.forename: Dana A
authors.initials: DA
authors.lastname: Davis
mesh_terms: D001233:Aspergillus nidulans / Q000235:genetics; D002176:Candida albicans / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C092394:PacC protein, Aspergillus; C489602:RIM101 protein, Candida albicans; D014157:Transcription Factors; D010450:Endopeptidases; D003546:Cysteine Endopeptidases