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Klimenko, V.* ; Reiners, J.* ; Applegate, V.* ; Reimann, K.* ; Popowicz, G.M. ; Hoeppner, A.* ; Papadopoulos, A.* ; Smits, S.H.J.* ; Nowack, E.C.M.*

The Paulinella chromatophore transit peptide part2 adopts a structural fold similar to the γ-glutamyl-cyclotransferase fold.

Plant Physiol. 199, 9 (2025)
Verlagsversion Postprint Forschungsdaten DOI PMC
Open Access Hybrid
Creative Commons Lizenzvertrag
The chromatophores of the cercozoan amoeba Paulinella are photosynthetic organelles that evolved from a cyanobacterial endosymbiont. Many nucleus-encoded chromatophore-targeted proteins carry unusual N-terminal targeting signals termed crTPs, which are bipartite. crTPpart1 likely mediates trafficking through the secretory pathway and is cleaved off during import, but crTPpart2 remains attached to its cargo protein and its function is unknown. To unravel the functional role of crTPpart2, here we elucidated the structures of crTPpart2 from two different chromatophore-targeted proteins by X-ray crystallography at ∼2.3 Å resolution. Interestingly, the crTPpart2 of both proteins adopts a structural fold. Both structures share a conserved structured core and a flexible N-terminal arm. The structured core resembles proteins of the γ-glutamyl cyclotransferase superfamily within which crTPpart2 structures form a protein (sub)-family. The proposed catalytic center typical for proteins with cyclotransferase activity is not conserved in crTPpart2. A Cys pair that is conserved in crTPpart2 of many chromatophore-targeted proteins has been captured as a disulfide bridge. Together, our data suggest that chromatophore-targeted proteins are imported in their folded state and that the fold adopted by crTPpart2 plays a functional role during import. The characterization of its structure and flexibility provides important steps towards elucidating this protein translocation mechanism.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter Protein Import; Petra Iii; Scattering; Macromolecules; Organelle; Beamline; Coli
ISSN (print) / ISBN 0032-0889
e-ISSN 1532-2548
Zeitschrift Plant Physiology
Quellenangaben Band: 199, Heft: 2, Seiten: 9 Artikelnummer: , Supplement: ,
Verlag American Society of Plant Biologists (ASPB)
Verlagsort Journals Dept, 2001 Evans Rd, Cary, Nc 27513 Usa
Begutachtungsstatus Peer reviewed
Institut(e) Institute of Structural Biology (STB)
Förderungen SFB
INST
DFG