Oep23 forms an ion channel in the chloroplast outer envelope

Goetze, Tom A.; Patil, Manali; Jeshen, Ingrid; Bölter, Bettina; Grahl, Sabine; Soll, Jürgen

doi:10.1186/s12870-015-0445-1

Cited by 24 publications

(16 citation statements)

References 39 publications

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“…The list of differentially abundant proteins also contains two outer-envelope proteins (OEP23 [At2g17695] and OEP24 [At5g42960]). OEP23 and OEP24 exhibit amphiphilic helices or a b-barrel conformation and act as cation and anion channels, respectively (Goetze et al, 2015;Röhl et al, 1999). Accordingly, at least 28 of the 38 differentially Table 1.…”

Section: Cold Temperatures Alter the Protein Repertoire Of The Envelomentioning

confidence: 99%

Identification of Chloroplast Envelope Proteins with Critical Importance for Cold Acclimation

et al. 2020

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O.T. was responsible for chloroplast and envelope membrane purification, sample preparation for mass spectrometry (MS), freezingtolerance experiments, data analysis, and manuscript preparation; T.M. was responsible for general design of the MS-based experimental study, machine learning, data analysis, and manuscript preparation; D.Z. performed MS data processing and data analysis; F.S. and M.S. performed MS-based protein identification; I.H. edited the manuscript and completed the writing; I.K. and B.P. generated MEX1 overexpressor lines; and E.N. conceived the research plan and wrote the manuscript.

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Section: Cold Temperatures Alter the Protein Repertoire Of The Envelomentioning

confidence: 99%

Identification of Chloroplast Envelope Proteins with Critical Importance for Cold Acclimation

et al. 2020

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“…1, and Table S1]. Several porins are known to permit passage of solutes across the chloroplast OM (18,(33)(34)(35). Almost all of these transport systems are encoded in the nucleus and posttranslationally inserted into the plastid envelope membranes.…”

Section: Paucity Of Chromatophore-encoded Solute Transportersmentioning

confidence: 99%

The puzzle of metabolite exchange and identification of putative octotrico peptide repeat expression regulators in the nascent photosynthetic organelles ofPaulinella chromatophora

Oberleitner

Poschmann

Macorano

et al. 2020

Preprint

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The cercozoan amoeba Paulinella chromatophora contains photosynthetic organelles - termed chromatophores - that evolved from a cyanobacterium, independently from plastids in plants and algae. Despite the more recent origin of the chromatophore, it shows tight integration into the host cell. It imports hundreds of nucleus-encoded proteins, and diverse metabolites are exchanged across the two chromatophore envelope membranes. However, the limited set of chromatophore-encoded transporters appears insufficient for supporting metabolic connectivity or protein import. Furthermore, chromatophore-localized biosynthetic pathways as well as multiprotein complexes include proteins of dual genetic origin, suggesting coordination of gene expression levels between chromatophore and nucleus. These findings imply that similar to the situation in mitochondria and plastids, nuclear factors evolved that control metabolite exchange and gene expression in the chromatophore. Here we show by mass spectrometric analyses of enriched insoluble protein fractions that, unexpectedly, nucleus-encoded transporters are not inserted into the chromatophore inner envelope membrane. Thus, despite the apparent maintenance of its barrier function, canonical metabolite transporters are missing in this membrane. Instead we identified several expanded groups of short chromatophore-targeted orphan proteins. Members of one of these groups are characterized by a single transmembrane helix, and others contain amphipathic helices. We hypothesize that these proteins are involved in modulating membrane permeability. Furthermore, we identified an expanded family of chromatophore-targeted helical repeat proteins. These proteins show similar domain architectures as known organelle-targeted octotrico peptide repeat expression regulators in algae and plants suggesting their convergent evolution as nuclear regulators of gene expression levels in the chromatophore.ImportanceThe endosymbiotic acquisition of mitochondria and plastids >1 billion years ago was central for the evolution of eukaryotic life. However, owing to their ancient origin, these organelles provide only limited insights into the initial stages of organellogenesis. The chromatophore in Paulinella evolved ~100 million years ago and thus, offers the possibility to gain valuable insights into early stages and common rules in organelle evolution. Critical to organellogenesis appears to be the establishment of nuclear control over metabolite exchange and gene expression in the endosymbiont. Here we show that the mechanism generating metabolic connectivity of the chromatophore fundamentally differs from the one for mitochondria and plastids, but likely rather resembles the poorly understood mechanism in various bacterial endosymbionts in plants and insects. Furthermore, we describe a novel class of chromatophore-targeted helical repeat proteins which evolved convergently to plastid-targeted expression regulators and are likely involved in gene expression control in the chromatophore.

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“…After completing the work described in this article, evidence for five new (putative) OMPP families has appeared. (1) The Oep23 Family (1.B.77) includes a characterized OMPP in the outer envelope of chloroplasts [ 134 ]. Bacterial homologues, particularly from Actinobacteria, have been identified.…”

Section: Discussionmentioning

confidence: 99%

Properties and Phylogeny of 76 Families of Bacterial and Eukaryotic Organellar Outer Membrane Pore-Forming Proteins

Reddy

Saier

2016

PLoS ONE

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We here report statistical analyses of 76 families of integral outer membrane pore-forming proteins (OMPPs) found in bacteria and eukaryotic organelles. 47 of these families fall into one superfamily (SFI) which segregate into fifteen phylogenetic clusters. Families with members of the same protein size, topology and substrate specificities often cluster together. Virtually all OMPP families include only proteins that form transmembrane pores. Nine such families, all of which cluster together in the SFI phylogenetic tree, contain both α- and β-structures, are multi domain, multi subunit systems, and transport macromolecules. Most other SFI OMPPs transport small molecules. SFII and SFV homologues derive from Actinobacteria while SFIII and SFIV proteins derive from chloroplasts. Three families of actinobacterial OMPPs and two families of eukaryotic OMPPs apparently consist primarily of α-helices (α-TMSs). Of the 71 families of (putative) β-barrel OMPPs, only twenty could not be assigned to a superfamily, and these derived primarily from Actinobacteria (1), chloroplasts (1), spirochaetes (8), and proteobacteria (10). Proteins were identified in which two or three full length OMPPs are fused together. Family characteristic are described and evidence agrees with a previous proposal suggesting that many arose by adjacent β-hairpin structural unit duplications.

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Oep23 forms an ion channel in the chloroplast outer envelope

Cited by 24 publications

References 39 publications

Identification of Chloroplast Envelope Proteins with Critical Importance for Cold Acclimation

Identification of Chloroplast Envelope Proteins with Critical Importance for Cold Acclimation

The puzzle of metabolite exchange and identification of putative octotrico peptide repeat expression regulators in the nascent photosynthetic organelles ofPaulinella chromatophora

Properties and Phylogeny of 76 Families of Bacterial and Eukaryotic Organellar Outer Membrane Pore-Forming Proteins

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