Sireesha Kodru, Sreedhar Nellaepalli, Shin-Ichiro Ozawa, Chihiro Satoh, Hiroshi Kuroda, Ryouichi Tanaka, Katharine Guan, Marilyn Kobayashi, Phoi Tran, Sarah McCarthy, Setsuko Wakao, Krishna K. Niyogi, Yuichiro Takahashi
{"title":"绿色藻类莱茵衣藻 lhl3 突变体中的叶绿素-蛋白质复合物。","authors":"Sireesha Kodru, Sreedhar Nellaepalli, Shin-Ichiro Ozawa, Chihiro Satoh, Hiroshi Kuroda, Ryouichi Tanaka, Katharine Guan, Marilyn Kobayashi, Phoi Tran, Sarah McCarthy, Setsuko Wakao, Krishna K. Niyogi, Yuichiro Takahashi","doi":"10.1111/tpj.17071","DOIUrl":null,"url":null,"abstract":"<p>Chlorophylls <i>a</i> and <i>b</i> (Chl <i>a</i> and <i>b</i>) are involved in light harvesting, photochemical reactions, and electron transfer reactions in plants and green algae. The core complexes of the photosystems (PSI and PSII) associate with Chl <i>a</i>, while the peripheral antenna complexes (LHCI and LHCII) bind Chls <i>a</i> and <i>b</i>. One of the final steps of Chl biosynthesis is the conversion of geranylgeranylated Chls (Chls<sub>GG</sub>) to phytylated Chls by geranylgeranyl reductase (GGR). Here, we isolated and characterized a pale green mutant of the green alga <i>Chlamydomonas reinhardtii</i> that was very photosensitive and was unable to grow photoautotrophically. This mutant has a 16-bp deletion in the <i>LHL3</i> gene, which resulted in the loss of LHL3 and GGR and accumulated only Chls<sub>GG</sub>. The <i>lhl3</i> mutant cells grown in the dark accumulated PSII and PSI proteins at 25–50% of WT levels, lacked PSII activity, and retained a decreased PSI activity. The PSII and PSI proteins were depleted to trace amounts in the mutant cells grown in light. In contrast, the accumulation of LHCI and LHCII was unaffected except for LHCA3. Our results suggest that the replacement of Chls with Chls<sub>GG</sub> strongly affects the structural and functional integrity of PSII and PSI complexes but their associating LHC complexes to a lesser extent. Affinity purification of HA-tagged LHL3 confirmed the formation of a stable LHL3-GGR complex, which is vital for GGR stability. The LHL3-GGR complex contained a small amount of PSI complex assembly factors, suggesting a putative coupling between Chl synthesis and PSI complex assembly.</p>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"120 4","pages":"1577-1590"},"PeriodicalIF":6.2000,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/tpj.17071","citationCount":"0","resultStr":"{\"title\":\"Geranylgeranylated-chlorophyll-protein complexes in lhl3 mutant of the green alga Chlamydomonas reinhardtii\",\"authors\":\"Sireesha Kodru, Sreedhar Nellaepalli, Shin-Ichiro Ozawa, Chihiro Satoh, Hiroshi Kuroda, Ryouichi Tanaka, Katharine Guan, Marilyn Kobayashi, Phoi Tran, Sarah McCarthy, Setsuko Wakao, Krishna K. Niyogi, Yuichiro Takahashi\",\"doi\":\"10.1111/tpj.17071\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Chlorophylls <i>a</i> and <i>b</i> (Chl <i>a</i> and <i>b</i>) are involved in light harvesting, photochemical reactions, and electron transfer reactions in plants and green algae. The core complexes of the photosystems (PSI and PSII) associate with Chl <i>a</i>, while the peripheral antenna complexes (LHCI and LHCII) bind Chls <i>a</i> and <i>b</i>. One of the final steps of Chl biosynthesis is the conversion of geranylgeranylated Chls (Chls<sub>GG</sub>) to phytylated Chls by geranylgeranyl reductase (GGR). Here, we isolated and characterized a pale green mutant of the green alga <i>Chlamydomonas reinhardtii</i> that was very photosensitive and was unable to grow photoautotrophically. This mutant has a 16-bp deletion in the <i>LHL3</i> gene, which resulted in the loss of LHL3 and GGR and accumulated only Chls<sub>GG</sub>. The <i>lhl3</i> mutant cells grown in the dark accumulated PSII and PSI proteins at 25–50% of WT levels, lacked PSII activity, and retained a decreased PSI activity. The PSII and PSI proteins were depleted to trace amounts in the mutant cells grown in light. In contrast, the accumulation of LHCI and LHCII was unaffected except for LHCA3. Our results suggest that the replacement of Chls with Chls<sub>GG</sub> strongly affects the structural and functional integrity of PSII and PSI complexes but their associating LHC complexes to a lesser extent. Affinity purification of HA-tagged LHL3 confirmed the formation of a stable LHL3-GGR complex, which is vital for GGR stability. 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Geranylgeranylated-chlorophyll-protein complexes in lhl3 mutant of the green alga Chlamydomonas reinhardtii
Chlorophylls a and b (Chl a and b) are involved in light harvesting, photochemical reactions, and electron transfer reactions in plants and green algae. The core complexes of the photosystems (PSI and PSII) associate with Chl a, while the peripheral antenna complexes (LHCI and LHCII) bind Chls a and b. One of the final steps of Chl biosynthesis is the conversion of geranylgeranylated Chls (ChlsGG) to phytylated Chls by geranylgeranyl reductase (GGR). Here, we isolated and characterized a pale green mutant of the green alga Chlamydomonas reinhardtii that was very photosensitive and was unable to grow photoautotrophically. This mutant has a 16-bp deletion in the LHL3 gene, which resulted in the loss of LHL3 and GGR and accumulated only ChlsGG. The lhl3 mutant cells grown in the dark accumulated PSII and PSI proteins at 25–50% of WT levels, lacked PSII activity, and retained a decreased PSI activity. The PSII and PSI proteins were depleted to trace amounts in the mutant cells grown in light. In contrast, the accumulation of LHCI and LHCII was unaffected except for LHCA3. Our results suggest that the replacement of Chls with ChlsGG strongly affects the structural and functional integrity of PSII and PSI complexes but their associating LHC complexes to a lesser extent. Affinity purification of HA-tagged LHL3 confirmed the formation of a stable LHL3-GGR complex, which is vital for GGR stability. The LHL3-GGR complex contained a small amount of PSI complex assembly factors, suggesting a putative coupling between Chl synthesis and PSI complex assembly.
期刊介绍:
Publishing the best original research papers in all key areas of modern plant biology from the world"s leading laboratories, The Plant Journal provides a dynamic forum for this ever growing international research community.
Plant science research is now at the forefront of research in the biological sciences, with breakthroughs in our understanding of fundamental processes in plants matching those in other organisms. The impact of molecular genetics and the availability of model and crop species can be seen in all aspects of plant biology. For publication in The Plant Journal the research must provide a highly significant new contribution to our understanding of plants and be of general interest to the plant science community.