The caspase-like Gpi8 subunit of Candida albicans GPI transamidase is a metal-dependent endopeptidase

Sudisht Kumar Sah; Shailja Shefali; Anshuman Yadav; Punnag Som; Sneha Sudha Komath

doi:10.1016/j.bbrc.2020.02.008

The caspase-like Gpi8 subunit of Candida albicans GPI transamidase is a metal-dependent endopeptidase

Biochem Biophys Res Commun. 2020 Feb 18:S0006-291X(20)30268-0. doi: 10.1016/j.bbrc.2020.02.008. Online ahead of print.

Authors

Sudisht Kumar Sah¹, Shailja Shefali¹, Anshuman Yadav¹, Punnag Som¹, Sneha Sudha Komath²

Affiliations

¹ School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
² School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India. Electronic address: sskomath@mail.jnu.ac.in.

PMID: 32081427
DOI: 10.1016/j.bbrc.2020.02.008

Abstract

GPI anchored proteins (GPI-APs) act at the frontiers of cells, decoding environmental cues and determining host-pathogen interactions in several lower eukaryotes. They are also essential for viability in lower eukaryotes. The GPI biosynthetic pathway begins at the ER and follows a roughly linear pathway to generate the complete precursor (CP) glycolipid. The GPI transamidase (GPIT) transfers this glycolipid to the C-terminal end of newly translated proteins after removing their GPI attachment signal sequence (SS). The GPIT subunit that cleaves SS is Gpi8, a protein with a conserved Cys/His catalytic dyad typical of cysteine proteases. A CaGPI8 heterozygous mutant accumulates CPs and has reduced cell surface GPI-APs. Using a simple cell-free assay, we demonstrate that the heterozygous CaGPI8 strain has low endopeptidase activity as well. The revertant strain is restored in all these phenotypes. CaGpi8 is also shown to be a metalloenzyme, whose protease activity is sensitive to agents that modify Cys/His residues.

Keywords: Cell-free assay; Endopeptidase; GPI transamidase; Metabolic labelling; Metalloenzyme.