The cytochrome b_(6f)(Cyt b_(6f))complex is a multisubunit protein complex in chloroplast thylakoid membranes required for photosynthetic electron transport.Here we report the isolation and characterization of the new...The cytochrome b_(6f)(Cyt b_(6f))complex is a multisubunit protein complex in chloroplast thylakoid membranes required for photosynthetic electron transport.Here we report the isolation and characterization of the new tiny albino 1(nta1)mutant in Arabidopsis,which has severe defects in Cyt b_(6f) accumulation and chloroplast development.Gene cloning revealed that the nta1 phenotype was caused by disruption of a single nuclear gene,NTA1,which encodes an integral thylakoid membrane protein conserved across green algae and plants.Overexpression of NTA1 completely rescued the nta1 phenotype,and knockout of NTA1 in wild-type plants recapitulated the mutant phenotype.Loss of NTA1 function severely impaired the accumulation of multiprotein complexes related to photosynthesis in thylakoid membranes,particularly the components of Cyt b_(6f).NTA1 was shown to directly interact with four subunits(Cyt b6/PetB,PetD,PetG,and PetN)of Cyt b_(6f) through the DUF1279 domain and C-terminal sequence to mediate their assembly.Taken together,our results identify NTA1 as a new and key regulator of chloroplast development that plays essential roles in assembly of the Cyt b_(6f) complex by interacting with multiple Cyt b_(6f) subunits.展开更多
A lipid_depleted cytochrome b 6f (Cyt b 6f) preparation was obtained from spinach (Spinacia oleracea L.) chloroplasts. Upon reconstitution of this preparation with the membrane lipids purified from spinach thylakoid...A lipid_depleted cytochrome b 6f (Cyt b 6f) preparation was obtained from spinach (Spinacia oleracea L.) chloroplasts. Upon reconstitution of this preparation with the membrane lipids purified from spinach thylakoid, the effects of different membrane lipids on the electron transfer activity were studied. The results show that the electron transfer activity of Cyt b 6f is obviously stimulated to different extents, respectively, by monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), phosphatidylcholine (PC), phosphatidylglycerol (PG) and sulfoquinovosyldiacylglycerol (SQDG), and that the extents of stimulation may be closely related to the charge of the membrane lipids. The stimulation of non_charged lipids (MGDG, DGDG) and neutrally_charged lipid (PC) was high with a maximum enhancement of 89%, 75% and 77%, respectively; but the stimulation of two kinds of negatively_charged lipid (PG and SQDG) was relatively low with a maximum enhancement of 43% and 26%, respectively.展开更多
基金supported by the General Research Fund(CUHK codes 14121915,14148916,and 14104521)the Area of Excellence Scheme(AoE/M-403/16 and AoE/M-05/12)of the Research Grants Council(RGC)of Hong Kong+1 种基金the National Natural Science Foundation of China(NSFC)-RGC Joint Scheme(N_CUHK452/17)direct grants from the Chinese University of Hong Kong(CUHK).
文摘The cytochrome b_(6f)(Cyt b_(6f))complex is a multisubunit protein complex in chloroplast thylakoid membranes required for photosynthetic electron transport.Here we report the isolation and characterization of the new tiny albino 1(nta1)mutant in Arabidopsis,which has severe defects in Cyt b_(6f) accumulation and chloroplast development.Gene cloning revealed that the nta1 phenotype was caused by disruption of a single nuclear gene,NTA1,which encodes an integral thylakoid membrane protein conserved across green algae and plants.Overexpression of NTA1 completely rescued the nta1 phenotype,and knockout of NTA1 in wild-type plants recapitulated the mutant phenotype.Loss of NTA1 function severely impaired the accumulation of multiprotein complexes related to photosynthesis in thylakoid membranes,particularly the components of Cyt b_(6f).NTA1 was shown to directly interact with four subunits(Cyt b6/PetB,PetD,PetG,and PetN)of Cyt b_(6f) through the DUF1279 domain and C-terminal sequence to mediate their assembly.Taken together,our results identify NTA1 as a new and key regulator of chloroplast development that plays essential roles in assembly of the Cyt b_(6f) complex by interacting with multiple Cyt b_(6f) subunits.
基金supported by grants from the "973" Programs(2009CB118501 and 2011CBA00901)the National Natural Science Foundation of China(30900095)+1 种基金Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(LYM11025)the Fundamental Research Funds for the Central Universities(11612325 and 11612352)~~
基金The State Key Basic Research and Development Plan(G1998010100)Innovative Foundation of Laboratory of Photosynthesis Basic Research Insitute of Botany,The Chinese Academy of Sciences
文摘A lipid_depleted cytochrome b 6f (Cyt b 6f) preparation was obtained from spinach (Spinacia oleracea L.) chloroplasts. Upon reconstitution of this preparation with the membrane lipids purified from spinach thylakoid, the effects of different membrane lipids on the electron transfer activity were studied. The results show that the electron transfer activity of Cyt b 6f is obviously stimulated to different extents, respectively, by monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), phosphatidylcholine (PC), phosphatidylglycerol (PG) and sulfoquinovosyldiacylglycerol (SQDG), and that the extents of stimulation may be closely related to the charge of the membrane lipids. The stimulation of non_charged lipids (MGDG, DGDG) and neutrally_charged lipid (PC) was high with a maximum enhancement of 89%, 75% and 77%, respectively; but the stimulation of two kinds of negatively_charged lipid (PG and SQDG) was relatively low with a maximum enhancement of 43% and 26%, respectively.
