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Dually localised proteins found in both the apicoplast and mitochondrion utilize the Golgi‐dependent pathway for apicoplast targeting in Toxoplasma gondii
Author(s) -
Prasad Aparna,
Mastud Pragati,
Patankar Swati
Publication year - 2021
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/boc.202000050
Subject(s) - apicoplast , golgi apparatus , biology , endoplasmic reticulum , organelle , microbiology and biotechnology , secretory pathway , plastid , biochemistry , gene , chloroplast
Background Information Like other apicomplexan parasites, Toxoplasma gondii harbours a four‐membraned endosymbiotic organelle – the apicoplast. Apicoplast proteins are nuclear encoded and trafficked to the organelle through the endoplasmic reticulum (ER). From the ER to the apicoplast, two distinct protein trafficking pathways can be used. One such pathway is the cell's secretory pathway involving the Golgi, whereas the other is a unique Golgi‐independent pathway. Using different experimental approaches, many apicoplast proteins have been shown to utilize the Golgi‐independent pathway, whereas a handful of reports show that a few proteins use the Golgi‐dependent pathway. This has led to an emphasis towards the unique Golgi‐independent pathway when apicoplast protein trafficking is discussed in the literature. Additionally, the molecular features that drive proteins to each pathway are not known. Results In this report, we systematically test eight apicoplast proteins, using a C‐terminal HDEL sequence to assess the role of the Golgi in their transport. We demonstrate that dually localised proteins of the apicoplast and mitochondrion ( Tg SOD2, Tg TPx1/2 and Tg ACN/IRP) are trafficked through the Golgi, whereas proteins localised exclusively to the apicoplast are trafficked independent of the Golgi. Mutants of the dually localised proteins that localised exclusively to the apicoplast also showed trafficking through the Golgi. Phylogenetic analysis of Tg SOD2, Tg TPx1/2 and Tg ACN/IRP suggested that the evolutionary origins of Tg SOD2 and Tg TPx1/2 lie in the mitochondrion, whereas Tg ACN/IRP appears to have originated from the apicoplast. Conclusions and Significance Collectively, with these results, for the first time, we establish that the driver of the Golgi‐dependent trafficking route to the apicoplast is the dual localisation of the protein to the apicoplast and the mitochondrion.