Structure and Conservation of the Periplasmic Targeting Factor Tic22 Protein from Plants and Cyanobacteria

Tripp, Joanna; Hahn, Alexander; Koenig, Patrick; Flinner, Nadine; Bublak, Daniela; Brouwer, Eva M.; Ertel, Franziska; Mirus, Oliver; Sinning, Irmgard; Tews, Ivo; Schleiff, Enrico

doi:10.1074/jbc.m112.341644

Cited by 36 publications

(59 citation statements)

References 57 publications

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“…Interestingly, in the cyanobacterium Anabaena sp. PCC 7120, a Tic22 homolog has also been shown to directly interact with the POTRA domains of a Toc75 homolog (Tripp et al, 2012). Therefore, not only has the orientation of Toc75 POTRA domains been preserved during evolution, as we show here, but the functional and physical interaction of POTRA domains with Tic22 in the IMS has also been preserved.…”

Section: Discussionmentioning

confidence: 57%

Polypeptide Transport-Associated Domains of the Toc75 Channel Protein Are Located in the Intermembrane Space of Chloroplasts

Chen

2016

Plant Physiol.

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Toc75 is the channel for protein translocation across the chloroplast outer envelope membrane. Toc75 belongs to the Omp85 protein family and consists of three N-terminal polypeptide transport-associated (POTRA) domains that are essential for the functions of Toc75, followed by a membrane-spanning b-barrel domain. In bacteria, POTRA domains of Omp85 family members are located in the periplasm, where they interact with other partner proteins to accomplish protein secretion and outer membrane protein assembly. However, the orientation and therefore the molecular function of chloroplast Toc75 POTRA domains remain a matter of debate. We investigated the topology of Toc75 using bimolecular fluorescence complementation and immunogold electron microscopy. Bimolecular fluorescence complementation analyses showed that in stably transformed plants, Toc75 N terminus is located on the intermembrane space side, not the cytosolic side, of the outer membrane. Immunogold labeling of endogenous Toc75 POTRA domains in pea (Pisum sativum) and Arabidopsis (Arabidopsis thaliana) confirmed that POTRA domains are located in the intermembrane space of the chloroplast envelope.

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Section: Discussionmentioning

confidence: 57%

Polypeptide Transport-Associated Domains of the Toc75 Channel Protein Are Located in the Intermembrane Space of Chloroplasts

Chen

2016

Plant Physiol.

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“…Intriguingly, when we plotted conserved residues of Tic22 from algal, plant and parasite species (supplemental Fig. S1) onto the surface of the structure, most were located within these two grooves, and similar grooves are found on the bacterial Tic22 homologue (15) (Fig. 4B).…”

Section: Resultsmentioning

confidence: 87%

“…Whether these interactions occur simultaneously or transiently is uncertain, and roles for Tic22 in either bridging the TIC and TOC complexes, or in shuttling translocated proteins between the two have been proposed (3). A recent study of a cyanobacterial Tic22 homologue proposes a role of Tic22 in bacterial outer membrane biogenesis, perhaps functioning as a chaperone (15).…”

mentioning

confidence: 99%

Tic22 Is an Essential Chaperone Required for Protein Import into the Apicoplast

Glaser

Dooren

Agrawal

et al. 2012

Journal of Biological Chemistry

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Background: Tic22 is a core protein import machinery component of chloroplasts and apicoplasts. Results: Tic22 is a chaperone, required for parasite survival and for protein import in the apicoplast. Conclusion: Tic22 lies between the plastid membranes, maintaining imported proteins unfolded for translocation. Significance: Chaperones which hold proteins in an unfolded state are central to membrane translocation systems and Tic22 plays this role in plastids.

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“…This suggests that in AFS-I-Omp85, the assembly of HgdD is not disturbed. Furthermore, the mutants of the other two Omp85-like genes (alr0075 and alr4893) (54,57,58) do not show an overlapping phenotype with the hgdD mutant (59) with respect to heterocyst development (5) or the sensitivity of AFS-I-hgdD to 30 mM lysozyme (59). A function of Alr0075 in HgdD insertion and assembly is further unlikely because this Omp85-like protein only exists in vegetative cells (54), whereas the expression of hgdD is enhanced in heterocysts (5).…”

Section: An Anaomp85-independent Insertion Of Hgdd Into the Outermentioning

confidence: 98%

The TolC-like Protein HgdD of the Cyanobacterium Anabaena sp. PCC 7120 Is Involved in Secondary Metabolite Export and Antibiotic Resistance

Hahn

Stevanovic

Mirus

et al. 2012

Journal of Biological Chemistry

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Background:The metabolite and antibiotic export system of cyanobacteria is largely unexplored. Results: Uptake of ethidium bromid by Anabaena sp. depends on porin-type activity while its seceretion relies on HgdD. Conclusion:The antibiotic export of cyanobacteria involves a proton gradient-driven TolC activity and MFS-type proteins. Significance: TolC of Anabaena sp. is placed in the context of antibiotic uptake and export.

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Structure and Conservation of the Periplasmic Targeting Factor Tic22 Protein from Plants and Cyanobacteria

Cited by 36 publications

References 57 publications

Polypeptide Transport-Associated Domains of the Toc75 Channel Protein Are Located in the Intermembrane Space of Chloroplasts

Polypeptide Transport-Associated Domains of the Toc75 Channel Protein Are Located in the Intermembrane Space of Chloroplasts

Tic22 Is an Essential Chaperone Required for Protein Import into the Apicoplast

The TolC-like Protein HgdD of the Cyanobacterium Anabaena sp. PCC 7120 Is Involved in Secondary Metabolite Export and Antibiotic Resistance

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