Ras hyperactivation versus overexpression: Lessons from Ras dynamics in Candida albicans

Vavilala A Pratyusha, Guiliana Soraya Victoria, Mohammad Firoz Khan, Dominic T Haokip, Bhawna Yadav, Nibedita Pal, Subhash Chandra Sethi, Priyanka Jain, Sneh Lata Singh, Sobhan Sen, Sneha Sudha Komath

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Ras signaling in response to environmental cues is critical for cellular morphogenesis in eukaryotes. This signaling is tightly regulated and its activation involves multiple players. Sometimes Ras signaling may be hyperactivated. In C. albicans, a human pathogenic fungus, we demonstrate that dynamics of hyperactivated Ras1 (Ras1G13V or Ras1 in Hsp90 deficient strains) can be reliably differentiated from that of normal Ras1 at (near) single molecule level using fluorescence correlation spectroscopy (FCS). Ras1 hyperactivation results in significantly slower dynamics due to actin polymerization. Activating actin polymerization by jasplakinolide can produce hyperactivated Ras1 dynamics. In a sterol-deficient hyperfilamentous GPI mutant of C. albicans too, Ras1 hyperactivation results from Hsp90 downregulation and causes actin polymerization. Hyperactivated Ras1 co-localizes with G-actin at the plasma membrane rather than with F-actin. Depolymerizing actin with cytochalasin D results in faster Ras1 dynamics in these and other strains that show Ras1 hyperactivation. Further, ergosterol does not influence Ras1 dynamics.

Original languageEnglish
Article number5248
JournalScientific Reports
Early online date27 Mar 2018
Publication statusPublished - 2018

Bibliographical note

We thank Prof. Neta Dean for the CIp10ADH1-Cherry plasmid and Prof. Aaron Mitchell for the BWP17 strain. We gratefully acknowledge Prof. Sudipta Maiti, TIFR, Mumbai, India for providing the data acquisition software. We also appreciate the feedback and discussions with Dr. Rohini Muthuswami, SLS, JNU as well as from the Protein Society group, New Delhi while this study was taking shape. We thank Prof. Alok Bhattacharya for Cytochalasin D. The GC-MS and fluorescence lifetime measurements were carried out at the Advanced Instrumentation Research Facility (AIRF), JNU. Confocal images were recorded either at the central instrumentation facility (CIF), SLS, JNU or at AIRF, JNU. This work was supported by project grants from Department of Biotechnology (DBT, Project grant no. BT/PR20410/BRB/10/1542/2016) and Department of Science and Technology (DST, Project grant no. SB/SO/BB-011/2014), India to S.S.K; and project grants from Department of Information Technology, (DIT, Project grant no. 12(4)/2007-PDD), India to S.S. for FCS setup. In addition, both S.S. and S.S.K. thank DBT-BUILDER for funding support (Project grant no. BT/PR5006/INF/153/2012). S.S.K. also acknowledges funding support from UGC Resource Networking grant to the School of Life Sciences. We thank DST-PURSE and JNU for assistance with funding for publication. G.S.V. and S.C.S. received a fellowship from UGC; V.A.P., B.Y., P.J., N.P., M.F.K. acknowledge CSIR for fellowships. S.L.S. received a fellowship from ICMR. D.T.H. and M.F.K. thank DBT-BUILDER for funding.


  • Journal Article
  • Cell signalling
  • Fluorescence specrometry
  • Fungal biology
  • Membrane biophysics


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