Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth.
Many apicomplexan parasites harbor a non-photosynthetic plastid called the apicoplast, which hosts important metabolic pathways like the methylerythritol 4-phosphate (MEP) pathway that synthesizes isoprenoid precursors. Yet many details in apicoplast metabolism are not well understood. In this study...
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2022-11-01
|
| Series: | PLoS Pathogens |
| Online Access: | https://doi.org/10.1371/journal.ppat.1011009 |
| _version_ | 1797973975106584576 |
|---|---|
| author | Zhipeng Niu Shu Ye Jiaojiao Liu Mengyu Lyu Lilan Xue Muxiao Li Congcong Lyu Junlong Zhao Bang Shen |
| author_facet | Zhipeng Niu Shu Ye Jiaojiao Liu Mengyu Lyu Lilan Xue Muxiao Li Congcong Lyu Junlong Zhao Bang Shen |
| author_sort | Zhipeng Niu |
| collection | DOAJ |
| description | Many apicomplexan parasites harbor a non-photosynthetic plastid called the apicoplast, which hosts important metabolic pathways like the methylerythritol 4-phosphate (MEP) pathway that synthesizes isoprenoid precursors. Yet many details in apicoplast metabolism are not well understood. In this study, we examined the physiological roles of four glycolytic enzymes in the apicoplast of Toxoplasma gondii. Many glycolytic enzymes in T. gondii have two or more isoforms. Endogenous tagging each of these enzymes found that four of them were localized to the apicoplast, including pyruvate kinase2 (PYK2), phosphoglycerate kinase 2 (PGK2), triosephosphate isomerase 2 (TPI2) and phosphoglyceraldehyde dehydrogenase 2 (GAPDH2). The ATP generating enzymes PYK2 and PGK2 were thought to be the main energy source of the apicoplast. Surprisingly, deleting PYK2 and PGK2 individually or simultaneously did not cause major defects on parasite growth or virulence. In contrast, TPI2 and GAPDH2 are critical for tachyzoite proliferation. Conditional depletion of TPI2 caused significant reduction in the levels of MEP pathway intermediates and led to parasite growth arrest. Reconstitution of another isoprenoid precursor synthesis pathway called the mevalonate pathway in the TPI2 depletion mutant partially rescued its growth defects. Similarly, knocking down the GAPDH2 enzyme that produces NADPH also reduced isoprenoid precursor synthesis through the MEP pathway and inhibited parasite proliferation. In addition, it reduced de novo fatty acid synthesis in the apicoplast. Together, these data suggest a model that the apicoplast dwelling TPI2 provides carbon source for the synthesis of isoprenoid precursor, whereas GAPDH2 supplies reducing power for pathways like MEP, fatty acid synthesis and ferredoxin redox system in T. gondii. As such, both enzymes are critical for parasite growth and serve as potential targets for anti-toxoplasmic intervention designs. On the other hand, the dispensability of PYK2 and PGK2 suggest additional sources for energy in the apicoplast, which deserves further investigation. |
| first_indexed | 2024-04-11T04:11:37Z |
| format | Article |
| id | doaj.art-30d056a735ba43788db9d4069201c575 |
| institution | Directory Open Access Journal |
| issn | 1553-7366 1553-7374 |
| language | English |
| last_indexed | 2024-04-11T04:11:37Z |
| publishDate | 2022-11-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Pathogens |
| spelling | doaj.art-30d056a735ba43788db9d4069201c5752023-01-01T05:31:33ZengPublic Library of Science (PLoS)PLoS Pathogens1553-73661553-73742022-11-011811e101100910.1371/journal.ppat.1011009Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth.Zhipeng NiuShu YeJiaojiao LiuMengyu LyuLilan XueMuxiao LiCongcong LyuJunlong ZhaoBang ShenMany apicomplexan parasites harbor a non-photosynthetic plastid called the apicoplast, which hosts important metabolic pathways like the methylerythritol 4-phosphate (MEP) pathway that synthesizes isoprenoid precursors. Yet many details in apicoplast metabolism are not well understood. In this study, we examined the physiological roles of four glycolytic enzymes in the apicoplast of Toxoplasma gondii. Many glycolytic enzymes in T. gondii have two or more isoforms. Endogenous tagging each of these enzymes found that four of them were localized to the apicoplast, including pyruvate kinase2 (PYK2), phosphoglycerate kinase 2 (PGK2), triosephosphate isomerase 2 (TPI2) and phosphoglyceraldehyde dehydrogenase 2 (GAPDH2). The ATP generating enzymes PYK2 and PGK2 were thought to be the main energy source of the apicoplast. Surprisingly, deleting PYK2 and PGK2 individually or simultaneously did not cause major defects on parasite growth or virulence. In contrast, TPI2 and GAPDH2 are critical for tachyzoite proliferation. Conditional depletion of TPI2 caused significant reduction in the levels of MEP pathway intermediates and led to parasite growth arrest. Reconstitution of another isoprenoid precursor synthesis pathway called the mevalonate pathway in the TPI2 depletion mutant partially rescued its growth defects. Similarly, knocking down the GAPDH2 enzyme that produces NADPH also reduced isoprenoid precursor synthesis through the MEP pathway and inhibited parasite proliferation. In addition, it reduced de novo fatty acid synthesis in the apicoplast. Together, these data suggest a model that the apicoplast dwelling TPI2 provides carbon source for the synthesis of isoprenoid precursor, whereas GAPDH2 supplies reducing power for pathways like MEP, fatty acid synthesis and ferredoxin redox system in T. gondii. As such, both enzymes are critical for parasite growth and serve as potential targets for anti-toxoplasmic intervention designs. On the other hand, the dispensability of PYK2 and PGK2 suggest additional sources for energy in the apicoplast, which deserves further investigation.https://doi.org/10.1371/journal.ppat.1011009 |
| spellingShingle | Zhipeng Niu Shu Ye Jiaojiao Liu Mengyu Lyu Lilan Xue Muxiao Li Congcong Lyu Junlong Zhao Bang Shen Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth. PLoS Pathogens |
| title | Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth. |
| title_full | Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth. |
| title_fullStr | Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth. |
| title_full_unstemmed | Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth. |
| title_short | Two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for Toxoplasma growth. |
| title_sort | two apicoplast dwelling glycolytic enzymes provide key substrates for metabolic pathways in the apicoplast and are critical for toxoplasma growth |
| url | https://doi.org/10.1371/journal.ppat.1011009 |
| work_keys_str_mv | AT zhipengniu twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT shuye twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT jiaojiaoliu twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT mengyulyu twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT lilanxue twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT muxiaoli twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT congconglyu twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT junlongzhao twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth AT bangshen twoapicoplastdwellingglycolyticenzymesprovidekeysubstratesformetabolicpathwaysintheapicoplastandarecriticalfortoxoplasmagrowth |