Universität zu Köln

Oberleitner, Linda, Perrar, Andreas, Macorano, Luis, Huesgen, Pitter F. and Nowack, Eva C. M. (2022). A bipartite chromatophore transit peptide and N-terminal protein processing in the Paulinella chromatophore. Plant Physiol., 189 (1). S. 152 - 165. CARY: OXFORD UNIV PRESS INC. ISSN 1532-2548

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Abstract

Proteins targeted to the evolutionary-early-stage photosynthetic organelle of Paulinella carry a bipartite N-terminal targeting sequence that is only partially removed upon protein import. The amoeba Paulinella chromatophora contains photosynthetic organelles, termed chromatophores, which evolved independently from plastids in plants and algae. At least one-third of the chromatophore proteome consists of nucleus-encoded (NE) proteins that are imported across the chromatophore double envelope membranes. Chromatophore-targeted proteins exceeding 250 amino acids (aa) carry a conserved N-terminal extension presumably involved in protein targeting, termed the chromatophore transit peptide (crTP). Short imported proteins do not carry discernable targeting signals. To explore whether the import of proteins is accompanied by their N-terminal processing, here we identified N-termini of 208 chromatophore-localized proteins by a mass spectrometry-based approach. Our study revealed extensive N-terminal acetylation and proteolytic processing in both NE and chromatophore-encoded (CE) fractions of the chromatophore proteome. Mature N-termini of 37 crTP-carrying proteins were identified, of which 30 were cleaved in a common processing region. Surprisingly, only the N-terminal similar to 50 aa (part 1) become cleaved upon import. This part contains a conserved adaptor protein-1 complex-binding motif known to mediate protein sorting at the trans-Golgi network followed by a predicted transmembrane helix, implying that part 1 anchors the protein co-translationally in the endoplasmic reticulum and mediates trafficking to the chromatophore via the Golgi. The C-terminal part 2 contains conserved secondary structural elements, remains attached to the mature proteins, and might mediate translocation across the chromatophore inner membrane. Short imported proteins remain largely unprocessed. Finally, this work illuminates N-terminal processing of proteins encoded in an evolutionary-early-stage organelle and suggests host-derived posttranslationally acting factors involved in regulation of the CE chromatophore proteome.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Oberleitner, Linda UNSPECIFIED UNSPECIFIED UNSPECIFIED Perrar, Andreas UNSPECIFIED UNSPECIFIED UNSPECIFIED Macorano, Luis UNSPECIFIED UNSPECIFIED UNSPECIFIED Huesgen, Pitter F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nowack, Eva C. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-676061
DOI:	10.1093/plphys/kiac012
Journal or Publication Title:	Plant Physiol.
Volume:	189
Number:	1
Page Range:	S. 152 - 165
Date:	2022
Publisher:	OXFORD UNIV PRESS INC
Place of Publication:	CARY
ISSN:	1532-2548
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PHOTOSYNTHETIC ORGANELLES; SECRETORY PATHWAY; IMPORT; IDENTIFICATION; EXPRESSION; SEQUENCE; GENES; GOLGI Multiple languages Plant Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/67606