Ion Channels in the Chloroplast Envelope Membrane

Biochemistry ◽  
1995 ◽  
Vol 34 (49) ◽  
pp. 15906-15917 ◽  
Author(s):  
Thomas Heibert ◽  
Thomas Steinkamp ◽  
Silke Hinnah ◽  
Martin Schwarz ◽  
Ulf-Ingo Flueggel ◽  
...  
Keyword(s):  
Ion Channels ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Envelope Membrane

scholarly journals Two plastid POLLUX ion channel-like proteins are required for stress-triggered stromal Ca2+ release

2021 ◽  
Author(s):  
Carsten Völkner ◽  
Lorenz Josef Holzner ◽  
Philip M Day ◽  
Amra Dhabalia Ashok ◽  
Jan de Vries ◽  
...  
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Chloroplast Envelope ◽  
Mycorrhizal Symbiosis ◽  
Intermembrane Space ◽  
Envelope Membrane ◽  
Loss Of Function ◽  
Chloroplast Envelope Membrane ◽  
Envelope Membranes ◽  
Yeast Mutants

Abstract Two decades ago, large cation currents were discovered in the envelope membranes of Pisum sativum L. (pea) chloroplasts. The deduced K+-permeable channel was coined fast-activating chloroplast cation (FACC) channel but its molecular identity remained elusive. To reveal candidates, we mined proteomic datasets of isolated pea envelopes. Our search uncovered distant members of the nuclear POLLUX ion channel family. Since pea is not amenable to molecular genetics, we used Arabidopsis thaliana to characterize the two gene homologs. Using several independent approaches, we show that both candidates localize to the chloroplast envelope membrane. The proteins, designated PLASTID ENVELOPE ION CHANNELS (PEC1/2), form oligomers with regulator of K+ conductance (RCK) domains protruding into the intermembrane space. Heterologous expression of PEC1/2 rescues yeast mutants deficient in K+ uptake. Nuclear POLLUX ion channels cofunction with Ca2+ channels to generate Ca2+ signals, critical for establishing mycorrhizal symbiosis and root development. Chloroplasts also exhibit Ca2+ transients in the stroma, probably to relay abiotic and biotic cues between plastids and the nucleus via the cytosol. Our results show that pec1pec2 loss-of-function double mutants fail to trigger the characteristic stromal Ca2+ release observed in wild-type plants exposed to external stress stimuli. Besides this molecular abnormality, pec1pec2 double mutants do not show obvious phenotypes. Future studies of PEC proteins will help to decipher the plant’s stress-related Ca2+ signaling network and the role of plastids. More importantly, the discovery of PECs in the envelope membrane is another critical step towards completing the chloroplast ion transport protein inventory.

scholarly journals The transit sequence mediates the specific interaction of the precursor of ferredoxin with chloroplast envelope membrane lipids.

1993 ◽  
Vol 268 (6) ◽  
pp. 4037-4042
Author(s):  
R. van't Hof ◽  
W. van Klompenburg ◽  
M. Pilon ◽  
A. Kozubek ◽  
G. de Korte-Kool ◽  
...  
Keyword(s):  
Membrane Lipids ◽  
Specific Interaction ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Envelope Membrane

How SFR2 is regulated to confer freezing tolerance of the chloroplast envelope membrane

2020 ◽  
Vol 34 (S1) ◽  
pp. 1-1
Author(s):  
Rebecca L. Roston ◽  
Allison C. Barnes ◽  
Zachary Shomo ◽  
Samantha Surber ◽  
Jennifer Myers
Keyword(s):  
Freezing Tolerance ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Envelope Membrane

scholarly journals Redox Transfer across the Inner Chloroplast Envelope Membrane

1991 ◽  
Vol 95 (4) ◽  
pp. 1131-1137 ◽  
Author(s):  
Dieter Heineke ◽  
Burgi Riens ◽  
Heike Grosse ◽  
Petra Hoferichter ◽  
Ute Peter ◽  
...  
Keyword(s):  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Envelope Membrane

scholarly journals Functional Analysis of Rice Long-Chain Acyl-CoA Synthetase 9 (OsLACS9) in the Chloroplast Envelope Membrane

2020 ◽  
Vol 21 (6) ◽  
pp. 2223
Author(s):  
Aya Kitajima-Koga ◽  
Marouane Baslam ◽  
Yuuki Hamada ◽  
Namiko Ito ◽  
Tomoko Taniuchi ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Fatty Acyl ◽  
Laser Scanning Microscopy ◽  
Chloroplast Envelope ◽  
Confocal Laser ◽  
Starch Degradation ◽  
Envelope Membrane ◽  
Chain Acyl ◽  
Chloroplast Envelope Membrane ◽  
Long Chain

The long-chain acyl-CoA synthetases (LACSs) are involved in lipid synthesis, fatty acid catabolism, and the transport of fatty acids between subcellular compartments. These enzymes catalyze the critical reaction of fatty acyl chains to fatty acyl-CoAs for the triacylglycerol biosynthesis used as carbon and energy reserves. In Arabidopsis, LACSs are encoded by a family of nine genes, with LACS9 being the only member located in the chloroplast envelope membrane. However, the comprehensive role of LACS9 and its contribution to plant metabolism have not been explored thoroughly. In this study, we report on the identification and characterization of LACS9 mutants in rice plants. Our results indicate that the loss-of-function mutations in OsLACS9 affect the architecture of internodes resulting in dwarf plants with large starch granules in the chloroplast, showing the suppression of starch degradation. Moreover, the plastid localization of α-amylase I-1 (AmyI-1)—a key enzyme involved in starch breakdown in plastids—was suppressed in the lacs9 mutant line. Immunological and confocal laser scanning microscopy analyses showed that OsLACS9-GFP is located in the chloroplast envelope in green tissue. Microscopic analysis showed that OsLACS9s interact with each other in the plastid envelope membrane. Furthermore, OsLACS9 is also one of the proteins transported to plastids without a transit peptide or involvement of the Toc/Tic complex system. To identify the plastid-targeting signal of OsLACS9, the transient expression and localization of a series of N-terminal truncated OsLACS9-green fluorescent protein (GFP) fusion proteins were examined. Truncation analyses identified the N-terminal 30 amino acid residues to be required for OsLACS9 plastid localization. Overall, the data in this study provide an advanced understanding of the function of OsLACS9 and its role in starch degradation and plant growth.

Comparative ultrastructure of eyespot membranes in gametes and zoospores of the green alga Ulva lactuca (Ulvales)

1981 ◽  
Vol 50 (1) ◽  
pp. 149-164
Author(s):  
H. Robenek ◽  
M. Melkonian
Keyword(s):  
Green Alga ◽  
Freeze Fracture ◽  
Size Class ◽  
Ulva Lactuca ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Membrane ◽  
Green Algal ◽  
Male Gametes ◽  
Chloroplast Envelope Membrane

Eyespot membranes in zoospores, and male and female gametes of the green alga Ulva lactuca, were studied comparatively by the freeze-fracture technique. The plasmalemma and the outer chloroplast envelope membrane overlying the eyespot lipid globules are specialized in all 3 types of reproductive cells. In the eyespot region the protoplasmic face (PF) of the outer chloroplast envelope membrane contains significantly more intramembraneous particles (IMP) compared to membrane areas outside the eyespot: in female gametes there are 2.5 times more IMP/micrometers 2, in zoospores 3 and in male gametes about 4. Small size-class IMP (4–6 nm diameter) are particularly abundant on both fracture faces of the outer chloroplast membrane, but size-class distribution is not significantly different between membrane areas inside and outside the eyespot region. The total number of IMP/eyespot on the PF of the outer chloroplast membrane was calculated to be 4900 in male gametes, 5500 in female gametes and 11 200 in zoospores. The results are discussed in accordance with the view that these membrane specializations participate in photoreception relating to green algal phototaxis. Evidence is presented that there is a correlation between IMP numbers per eyespot in the outer chloroplast envelope membrane and the different phototactic behaviour of gametes compared to zoospores in Ulva.

scholarly journals Low Density Membranes Are Associated with RNA-binding Proteins and Thylakoids in the Chloroplast of Chlamydomonas reinhardtii

1998 ◽  
Vol 140 (1) ◽  
pp. 101-110 ◽  
Author(s):  
William Zerges ◽  
Jean-David Rochaix
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Buoyant Density ◽  
Mrna Translation ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Chloroplast Envelope Membrane ◽  
Inner Envelope

Chloroplast subfractions were tested with a UV cross-linking assay for proteins that bind to the 5′ untranslated region of the chloroplast psbC mRNA of the green alga Chlamydomonas reinhardtii. These analyses revealed that RNA-binding proteins of 30–32, 46, 47, 60, and 80 kD are associated with chloroplast membranes. The buoyant density and the acyl lipid composition of these membranes are compatible with their origin being the inner chloroplast envelope membrane. However, unlike previously characterized inner envelope membranes, these membranes are associated with thylakoids. One of the membrane-associated RNA-binding proteins appears to be RB47, which has been reported to be a specific activator of psbA mRNA translation. These results suggest that translation of chloroplast mRNAs encoding thylakoid proteins occurs at either a subfraction of the chloroplast inner envelope membrane or a previously uncharacterized intra-chloroplast compartment, which is physically associated with thylakoids.

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