TY - JOUR
T1 - Cell cycle-regulated vesicular trafficking of Toxoplasma APT1, a protein localized to multiple apicoplast membranes
AU - Karnataki, Anuradha
AU - DeRocher, Amy
AU - Coppens, Isabelle
AU - Nash, Coral
AU - Feagin, Jean E.
AU - Parsons, Marilyn
PY - 2007/3
Y1 - 2007/3
N2 - The apicoplast is a relict plastid essential for viability of the apicomplexan parasites Toxoplasma and Plasmodium. It is surrounded by multiple membranes that proteins, substrates and metabolites must traverse. Little is known about apicoplast membrane proteins, much less their sorting mechanisms. We have identified two sets of apicomplexan proteins that are homologous to plastid membrane proteins that transport phosphosugars or their derivatives. Members of the first set bear N-terminal extensions similar to those that target proteins to the apicoplast lumen. While Toxoplasma gondii lacks this type of translocator, the N-terminal extension from the Plasmodium falciparum sequence was shown to be functional in T. gondii. The second set of translocators lacks an N-terminal targeting sequence. This translocator, TgAPT1, when tagged with HA, localized to multiple apicoplast membranes in T. gondii. Contrasting with the constitutive targeting of luminal proteins, the localization of the translocator varied during the cell cycle. Early-stage parasites showed circumplastid distribution, but as the plastid elongated in preparation for division, vesicles bearing TgAPT1 appeared adjacent to the plastid. After plastid division, the protein resumes a circumplastid colocalization. These studies demonstrate for the first time that vesicular trafficking likely plays a role in the apicoplast biogenesis.
AB - The apicoplast is a relict plastid essential for viability of the apicomplexan parasites Toxoplasma and Plasmodium. It is surrounded by multiple membranes that proteins, substrates and metabolites must traverse. Little is known about apicoplast membrane proteins, much less their sorting mechanisms. We have identified two sets of apicomplexan proteins that are homologous to plastid membrane proteins that transport phosphosugars or their derivatives. Members of the first set bear N-terminal extensions similar to those that target proteins to the apicoplast lumen. While Toxoplasma gondii lacks this type of translocator, the N-terminal extension from the Plasmodium falciparum sequence was shown to be functional in T. gondii. The second set of translocators lacks an N-terminal targeting sequence. This translocator, TgAPT1, when tagged with HA, localized to multiple apicoplast membranes in T. gondii. Contrasting with the constitutive targeting of luminal proteins, the localization of the translocator varied during the cell cycle. Early-stage parasites showed circumplastid distribution, but as the plastid elongated in preparation for division, vesicles bearing TgAPT1 appeared adjacent to the plastid. After plastid division, the protein resumes a circumplastid colocalization. These studies demonstrate for the first time that vesicular trafficking likely plays a role in the apicoplast biogenesis.
UR - http://www.scopus.com/inward/record.url?scp=33947301933&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33947301933&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2958.2007.05619.x
DO - 10.1111/j.1365-2958.2007.05619.x
M3 - Article
C2 - 17367386
AN - SCOPUS:33947301933
SN - 0950-382X
VL - 63
SP - 1653
EP - 1668
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 6
ER -