Yeast aminopeptidase I is post-translationally sorted from the cytosol to the vacuole by a mechanism mediated by its bipartite N-terminal extension.

Seguí‐Real, Bartolomé; Martinez, M. Pérez; Sandoval, Ignacio V.

doi:10.1002/j.1460-2075.1995.tb00234.x

Cited by 41 publications

(46 citation statements)

References 33 publications

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“…To assay complementation of autophagy, PbATG8 was expressed under the control of the PGK (phosphoglycerate kinase) promoter and processing of the precursor form of aminopeptidase I (prApe1) was monitored by western blotting. 35,36 As observed for the mammalian system, complementation was not observed upon induction of starvation (Fig. S6A).…”

Section: Plasmodium Atg8 Does Not Interact With the Mammalian Or Yeassupporting

confidence: 58%

Characterization of the ATG8-conjugation system in 2Plasmodiumspecies with special focus on the liver stage

et al. 2013

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Keywords: malaria, Plasmodium liver forms, cellular differentiation, autophagy-related genes, ATG8, apicoplast Abbreviations: ACP, acyl carrier protein; ATG, autophagy-related (gene); ATG, autophagy-related (protein); GABARAP, GABA(A) receptor-associated protein; GFP, green fluorescent protein; IEM, immunoelectron microscopy; IFA, immunofluorescence assays; LC3, microtubule-associated protein 1 light chain 3; mCherry, mCherry red fluorescent protein; ORF, open reading frame; PbATG3, Plasmodium berghei ATG3; PbATG7, Plasmodium berghei ATG7; PbATG8, Plasmodium berghei ATG8; PGK, phosphoglycerate kinase; PDM, product of the differences from the mean; PE, phosphatidylethanolamine; PfATG8, Plasmodium falciparum ATG8; p.i., post-infection; prApe1, precursor form of aminopeptidase I; PtdIns3P, phosphatidylinositol 3-phosphate; PV, parasitophorous vacuolePlasmodium parasites successfully colonize different habitats within mammals and mosquitoes, and adaptation to various environments is accompanied by changes in their organelle composition and size. Previously, we observed that during hepatocyte infection, Plasmodium discards organelles involved in invasion and expands those implicated in biosynthetic pathways. We hypothesized that this process is regulated by autophagy. Plasmodium spp. possess a rudimentary set of known autophagy-related proteins that includes the ortholog of yeast atg8. in this study, we analyzed the activity of the aTG8-conjugation pathway over the course of the lifecycle of Plasmodium falciparum and during the liver stage of Plasmodium berghei. We engineered a transgenic P. falciparum strain expressing mcherry-PfaTG8. These transgenic parasites expressed mcherry-PfaTG8 in human hepatocytes and erythrocytes, and in the midgut and salivary glands of Anopheles mosquitoes. in all observed stages, mcherry-PfaTG8 was localized to tubular structures. Our eM and colocalization studies done in P. berghei showed the association of PbaTG8 on the limiting membranes of the endosymbiont-derived plastid-like organelle known as the apicoplast. interestingly, during parasite replication in hepatocytes, the association of PbaTG8 with the apicoplast increases as this organelle expands in size. PbATG3, PbATG7 and PbATG8 are cotranscribed in all parasitic stages. Molecular analysis of PbaTG8 and PbaTG3 revealed a novel mechanism of interaction compared with that observed for other orthologs. This is further supported by the inability of Plasmodium aTG8 to functionally complement atg8Δ yeast or localize to autophagosomes in starved mammalian cells. altogether, these data suggests a unique role for the aTG8-conjugation system in Plasmodium parasites.

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Section: Plasmodium Atg8 Does Not Interact With the Mammalian Or Yeassupporting

confidence: 58%

Characterization of the ATG8-conjugation system in 2Plasmodiumspecies with special focus on the liver stage

et al. 2013

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“…The first of these forms an amphipathic structure; unlike mitochondrial targeting signals, the charged half is composed of both basic and acidic residues. Sitespecific mutagenesis was used to analyze the location of targeting information in the API propeptide (28,29). Small deletions anywhere within the first helix of the propeptide resulted in a complete block in targeting.…”

Section: The Aminopeptidase I Propeptide Is Requiredmentioning

confidence: 99%

Nonclassical Protein Sorting to the Yeast Vacuole

Klionsky

1998

Journal of Biological Chemistry

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“…Strikingly, despite all these differences, targeting of API to the vacuole is specific and saturable, both in vegetative growth conditions and under nitrogen deprivation (3), although the molecular details of its selective recognition and capture remain essentially unknown. Previous studies have shown that pAPI recognition by the transport machinery involves its prepro-amino extension (5,6) and cytoplasmic chaperones of the Ssa family (7,8). Furthermore, the amino extension is necessary and sufficient to target the reporter protein GFP to the vacuole (9).…”

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confidence: 99%

Yol082p, a Novel CVT Protein Involved in the Selective Targeting of Aminopeptidase I to the Yeast Vacuole

Leber¹,

Silles²,

Sandoval³

et al. 2001

Journal of Biological Chemistry

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The yeast vacuolar enzyme aminopeptidase I (API) is synthesized in the cytoplasm as a precursor (pAPI).Upon its assembly into dodecamers, pAPI is wrapped by double-membrane saccular structures for its further transport within vesicles that fuse with the vacuolar membrane and release their content in the vacuolar lumen. Targeting of API to the vacuole occurs by two alternative transport routes, the cvt and the autophagy pathways, which although mechanistically similar specifically operate under vegetative growth or nitrogen starvation conditions, respectively. We have studied the role of Yol082p, a protein identified by its ability to interact with API, in the transport of its precursor to the vacuole. We show that Yol082p interacts with mature API, an interaction that is strengthened by the amino extension of the API protein. Yol082p is required for targeting of pAPI to the vacuole, both under growing and short term nitrogen starvation conditions. Absence of Yol082p does not impede the assembly of pAPI into dodecamers, but precludes the enclosure of pAPI within transport vesicles. Microscopy studies show that during vegetative growth Yol082p is distributed between a cytoplasmic pool and a variable number of 0.13-0.27-m round, mobile structures, which are no longer observed under conditions of nitrogen starvation, and become larger in cells expressing the inactive Yol082⌬C32p, or lacking Apg12p. In contrast to the autophagy mutants involved in API transport, a ⌬yol082 strain does not lose viability under nitrogen starvation conditions, indicating normal function of the autophagy pathway. The data are consistent with a role of Yol082p in an early step of the API transport, after its assembly into dodecamers. Because Yol082p fulfills the functional requisites that define the CVT proteins, we propose to name it Cvt19.In the yeast Saccharomyces cerevisiae the vacuolar hydrolase leucine aminopeptidase I (API) 1 is synthesized in the cytoplasm as a precursor (pAPI) (1) and delivered to the vacuole by one of two alternative routes that operate under distinct physiological conditions: the cytoplasm to vacuole targeting (Cvt), in nutrient-rich conditions, and the autophagy (Apg) pathway, under starvation conditions (2). The Cvt pathway is constitutive and biosynthetic, while autophagy is nonselective and degradative and is induced to survive periods of nutrient limitation (3). However, the two pathways share many molecular components and both involve sequestration by double-membrane saccular structures of unknown origin that capture the load, close into vesicles, and then fuse with the vacuole (4). A major difference between these pathways appears to be the size and content of the transport vesicles. The Cvt vesicles exclude cytoplasm and are smaller than autophagosomes that engulf bulk cytoplasm and even organelles (2). Strikingly, despite all these differences, targeting of API to the vacuole is specific and saturable, both in vegetative growth conditions and under nitrogen deprivation (3), although the molecular detail...

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Yeast aminopeptidase I is post-translationally sorted from the cytosol to the vacuole by a mechanism mediated by its bipartite N-terminal extension.

Cited by 41 publications

References 33 publications

Characterization of the ATG8-conjugation system in 2Plasmodiumspecies with special focus on the liver stage

Characterization of the ATG8-conjugation system in 2Plasmodiumspecies with special focus on the liver stage

Nonclassical Protein Sorting to the Yeast Vacuole

Yol082p, a Novel CVT Protein Involved in the Selective Targeting of Aminopeptidase I to the Yeast Vacuole

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