Sec-independent protein translocation by the maize Hcf106 protein.
نویسندگان
چکیده
The bacterial Sec and signal recognition particle (ffh-dependent) protein translocation mechanisms are conserved between prokaryotes and higher plant chloroplasts. A third translocation mechanism in chloroplasts [the proton concentration difference (DeltapH) pathway] was previously thought to be unique. The hcf106 mutation of maize disrupts the localization of proteins transported through this DeltapH pathway in isolated chloroplasts. The Hcf106 gene encodes a receptor-like thylakoid membrane protein, which shows homology to open reading frames from all completely sequenced bacterial genomes, which suggests that the DeltapH pathway has been conserved since the endosymbiotic origin of chloroplasts. Thus, the third protein translocation pathway, of which HCF106 is a component, is found in both bacteria and plants.
منابع مشابه
The Maize tha4 Gene Functions in Sec-Independent Protein Transport in Chloroplasts and Is Related to hcf106, tatA, and tatB
Proteins are translocated across the chloroplast thylakoid membrane by a variety of mechanisms. Some proteins engage a translocation machinery that is derived from the bacterial Sec export system and require an interaction with a chloroplast-localized SecA homologue. Other proteins engage a machinery that is SecA-independent, but requires a transmembrane pH gradient. Recently, a counterpart to ...
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Prokaryotes and prokaryote-derived thylakoid membranes of chloroplasts share multiple, evolutionarily conserved pathways for protein export. These include the Sec, signal recognition particle (SRP), and Delta pH/Tat systems. Little is known regarding the thylakoid membrane components involved in these pathways. We isolated a cDNA clone to a novel component of the Delta pH pathway, Tha4, and pre...
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We describe the identification of two Escherichia coli genes required for the export of cofactor-containing periplasmic proteins, synthesized with signal peptides containing a twin arginine motif. Both gene products are homologous to the maize HCF106 protein required for the translocation of a subset of lumenal proteins across the thylakoid membrane. Disruption of either gene affects the export...
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The Delta pH pathway is one of two systems for protein transport to the thylakoid lumen. It is a novel transport system that requires only the thylakoidal DeltapH to power translocation. Several substrates of the Delta pH pathway, including the intermediate precursor form of OE17 (iOE17) and the truncated precursor form of OE17 (tOE17), were shown to bind to the membrane in the absence of the D...
متن کاملFunctional assembly of thylakoid deltapH-dependent/Tat protein transport pathway components in vitro.
Assembly of the components of the thylakoid deltapH-dependent/Tat protein transport machinery was analyzed in vitro. Upon incubation with intact chloroplasts, precursors to all three components, Hcf106, cpTatC and Tha4, were imported into the organelle and assembled into characteristic endogenous complexes. In particular, all of the imported cpTatC and approximately two-thirds of the imported H...
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ورودعنوان ژورنال:
- Science
دوره 278 5342 شماره
صفحات -
تاریخ انتشار 1997