Chaperone-assisted Post-translational Transport of Plastidic Type I Signal Peptidase 1

Endow, Joshua K.; Singhal, Rajneesh; Fernandez, Donna E.; Inoue, Kentaro

doi:10.1074/jbc.m115.684829

Cited by 26 publications

(22 citation statements)

References 73 publications

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“…It is likely that PsbO1 vigorously interacts with and needs protection from molecular chaperones before it is transported into thylakoid lumen; however, the interaction might be too weak and transient to be visualized by classical biochemical assays. The involvement of stroma chaperonin for thylakoid transport of plastidic type I signal peptidase has been recently reported [ 68 ]. By comparing two transgenic lines that bear the same PsbO1GFP allele, we showed that extra HSP90C facilitates the accumulation of PsbO1GFP mature form ( Fig 5B ) and more thylakoid association of GFP signal ( Fig 6 ).…”

Section: Discussionmentioning

confidence: 99%

HSP90C interacts with PsbO1 and facilitates its thylakoid distribution from chloroplast stroma in Arabidopsis

Jiang

Bonea

et al. 2017

PLoS ONE

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Arabidopsis plastidic HSP90C is an HSP90 family molecular chaperone that is required for chloroplast development and function. To understand the mechanism of action of HSP90C within the chloroplast, we conducted a yeast two-hybrid screening and revealed it interacts directly with the photosystem II extrinsic protein PsbO1, which performs a canonical function in the thylakoid lumen. To understand the biological significance of HSP90C-PsbO1 interaction, we investigated the role of HSP90C in modulating the stromal and thylakoid distribution of PsbO1GFP fusion protein. Fusion to GFP significantly delays the PsbO1 thylakoid transport and induces a variegation phenotype. Overexpression of HSP90C promotes the thylakoid distribution of PsbO1GFP and alleviates the leaf variegation. By tracking the chloroplast maturation during photomorphogenesis, we observed PsbO1GFP tends to form distinct fluorescent clusters within the stroma with delayed thylakoid membrane biogenesis, while HSP90C overexpression corrects these adverse effects. We also demonstrated that active HSP90C function is specifically required for stable accumulation of mature PsbO1GFP in thylakoid by using specific inhibitor geldanamycin. This study therefore not only identified novel HSP90C interactors, but also reports for the first time that PsbO1 enroute from the cytoplasm to thylakoid lumen is tightly regulated by the HSP90C chaperone complex in plastid stroma; whereas the proper HSP90C homeostasis is also critical for chloroplast maturation and function.

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Section: Discussionmentioning

confidence: 99%

HSP90C interacts with PsbO1 and facilitates its thylakoid distribution from chloroplast stroma in Arabidopsis

Jiang

Bonea

et al. 2017

PLoS ONE

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“…11,791,100;Invitrogen). The destination vector used for in vitro import and processing assays was pIVTGW-SP6, described in Endow et al (2015). The destination vector used for transient expression was pMDC32 (Curtis and Grossniklaus, 2003).…”

Section: Plasmidsmentioning

confidence: 99%

Chloroplast Outer Membrane β-Barrel Proteins Use Components of the General Import Apparatus

2019

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Chloroplasts evolved from a cyanobacterial endosymbiont that resided within a eukaryotic cell. Due to their prokaryotic heritage, chloroplast outer membranes contain transmembrane b-barrel proteins. While most chloroplast proteins use N-terminal transit peptides to enter the chloroplasts through the translocons at the outer and inner chloroplast envelope membranes (TOC/TIC), only one b-barrel protein, Toc75, has been shown to use this pathway. The route other b-barrel proteins use has remained unresolved. Here we use in vitro pea (Pisum sativum) chloroplast import assays and transient expression in Nicotiana benthamiana to address this. We show that a paralog of Toc75, outer envelope protein 80 kD (OEP80), also uses a transit peptide but has a distinct envelope sorting signal. Our results additionally indicate that b-barrels that do not use transit peptides also enter the chloroplast using components of the general import pathway.

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“…8N–Q ). As a control for non-specific effects in mutant protoplasts, we localized GFP fused to PLSP1, a thylakoid protein that is known to be targeted via an SRP-independent process ( Endow et al , 2015 ), in wild-type, srp43 , and srp54 protoplasts. PLSP1 has one TMD, a large C-terminus exposed to the thylakoid lumen, and a smaller N-terminus exposed to the stroma.…”

Section: Resultsmentioning

confidence: 99%

Sorting of SEC translocase SCY components to different membranes in chloroplasts

Singhal

Fernandez

2017

Journal of Experimental Botany

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Chaperone-assisted Post-translational Transport of Plastidic Type I Signal Peptidase 1

Cited by 26 publications

References 73 publications

HSP90C interacts with PsbO1 and facilitates its thylakoid distribution from chloroplast stroma in Arabidopsis

HSP90C interacts with PsbO1 and facilitates its thylakoid distribution from chloroplast stroma in Arabidopsis

Chloroplast Outer Membrane β-Barrel Proteins Use Components of the General Import Apparatus

Sorting of SEC translocase SCY components to different membranes in chloroplasts

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