Both mammalian PIG-M and PIG-X are required for growth of GPI14-disrupted yeast.
GPI mannosyltransferase I (GPI-MT-I) transfers the first mannose to a GPI-anchor precursor, glucosamine-(acyl)phosphatidylinositol [GlcN-(acyl)PI]. Mammalian GPI-MT-I consists of two components, PIG-M and PIG-X, which are homologous to Gpi14p and Pbn1p in Saccharomyces cerevisiae, respectively. In the present study, we disrupted yeast GPI14 and analysed the phenotype of gpi14 yeast. The gpi14 haploid cells were inviable and accumulated GlcN-(acyl)PI. We cloned PIG-M homologues from human, Plasmodium falciparum (PfPIG-M) and Trypanosoma brucei (TbGPI14), and tested whether they could complement gpi14-disrupted yeast. None of them restored GPI-MT-I activity and cell growth in gpi14-disrupted yeast. However, gpi14-disrupted yeast cells with human PIG-M, but not with PfPIG-M or TbGPI14, grew slowly but significantly when they were supplemented with rat PIG-X. This suggests that the association of PIG-X and PIG-M for GPI-MT-I activity is not interchangeable between mammals and the other lower eukaryotes.
Kim
Youn Uck
YU
Department of Biological Sciences, Sun Moon University, A-San City, Korea. kimyu@sunmoon.ac.kr
Ashida
Hisashi
H
Mori
Kenichiro
K
Maeda
Yusuke
Y
Hong
Yeongjin
Y
Kinoshita
Taroh
T
D000818:Animals; D005944:Glucosamine / Q000378:metabolism; D006801:Humans; D008364:Mannosyltransferases / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D010716:Phosphatidylinositols / Q000378:metabolism; D010963:Plasmodium falciparum / Q000201:enzymology; D015800:Protozoan Proteins / Q000378:metabolism; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000201:enzymology
D008565:Membrane Proteins; D010716:Phosphatidylinositols; C524413:Pigx protein, rat; D015800:Protozoan Proteins; D029701:Saccharomyces cerevisiae Proteins; D008364:Mannosyltransferases; C486036:PIGM protein, human; C423034:glycosylphosphatidylinositol mannosyltransferase I; D005944:Glucosamine