Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Among the protein translocation pathways of the thylakoid membrane in chloroplasts, the DeltapH/TAT pathway is unique in several aspects. In vitro transport assays with isolated chloroplasts or thylakoids have defined the trans-thylakoidal proton gradient as the sole requirement for effecting transport. From these studies, evidence has also accumulated indicating that, in contrast to the remaining protein transport pathways present in the thylakoid membrane, the DeltapH/TAT pathway is able to mediate the transport of folded proteins. The present work has established a novel approach to demonstrate the transport of folded proteins by this pathway in vivo. For this purpose, Arabidopsis thaliana plants were stably transformed with gene constructs expressing enhanced green fluorescent protein (EGFP) alone or fused to the transit peptides of different chloroplast proteins under the control of the 35S CAMV promoter. The intracellular and intraorganellar distribution of EGFP in the resulting transformants showed that while all the chloroplast transit peptides efficiently mediated the transport of EGFP into plastids, only those specific for the DeltapH/TAT pathway were able to direct the protein into the thylakoid lumen as well. This could be demonstrated both by fluorescence and immunoelectron microscopy. Analysis of isolated and fractionated chloroplasts using western blot and spectrofluorometric assays confirmed the presence of folded EGFP solely within the thylakoid lumen of these lines. These results strongly suggest that the protein adopts a folded state in the chloroplast stroma and thus, can only be translocated further into the chloroplast lumen by the DeltapH/TAT pathway.
J Exp Bot 2004 Aug
PMID:In vivo transport of folded EGFP by the DeltapH/TAT-dependent pathway in chloroplasts of Arabidopsis thaliana. 1520 33

In the Scots pine (Pinus sylvestris L.) seed, embryos grow and develop within the corrosion cavity of the megagametophyte, a maternally derived haploid tissue, which houses the majority of the storage reserves of the seed. In the present study, histochemical methods and quantification of the expression levels of the programmed cell death (PCD) and DNA repair processes related genes (MCA, TAT-D, RAD51, KU80, and LIG) were used to investigate the physiological events occurring in the megagametophyte tissue during embryo development. It was found that the megagametophyte was viable from the early phases of embryo development until the early germination of mature seeds. However, the megagametophyte cells in the narrow embryo surrounding region (ESR) were destroyed by cell death with morphologically necrotic features. Their cell wall, plasma membrane, and nuclear envelope broke down with the release of cell debris and nucleic acids into the corrosion cavity. The occurrence of necrotic-like cell death in gymnosperm embryogenesis provides a favourable model for the study of developmental cell death with necrotic-like morphology and suggests that the mechanism underlying necrotic cell death is evolutionary conserved.
J Exp Bot 2009
PMID:One tissue, two fates: different roles of megagametophyte cells during Scots pine embryogenesis. 1924 93

Chloroplast stromal factors involved in regulating thylakoid protein targeting are poorly understood. We previously reported that in Arabidopsis thaliana, the stromal localized chaperone HSP90C interacted with the nuclear-encoded thylakoid lumen protein PsbO1 and suggested a role for HSP90C in aiding PsbO1 thylakoid targeting. Using in organello transport assays, particularly with model substrates naturally expressed in stroma, in this study we showed that light or exogenous ATP, and HSP90C activity were required for Sec-dependent transport of GFP led by PsbO1 thylakoid targeting sequence. Using a previously identified PsbO1T200A mutant, we provided evidence that a stronger interaction between HSP90C and PsbO1 better facilitated its stroma-thylakoid trafficking. We also showed that SecY1, the channel protein of the thylakoid SEC translocase, specifically interacted with HSP90C in vivo. Inhibition of the chaperone ATPase activity suppressed the association of PsbO1GFP-HSP90C complex to SecY1. Together with analyzing the expression and accumulation of a few other thylakoid proteins that utilize the SRP, TAT or SEC translocation pathways, we propose a model in which HSP90C forms a guiding complex that interacts with thylakoid protein precursors and assists in their specific targeting to the thylakoid SEC translocon.
J Exp Bot 2020 Aug 27
PMID:Plastid chaperone HSP90C guides precursor proteins to the SEC translocase for thylakoid transport. 3285 83