Dataset Information

The Paulinella chromatophore N-terminome

ABSTRACT: The cercozoan amoeba Paulinella chromatophora contains photosynthetic organelles - termed chromatophores - that evolved from a cyanobacterium ~100 million years ago, independently from plastids in plants and algae. Despite its more recent origin, at least one third of the chromatophore proteome consists of nucleus-encoded proteins that are imported by an unknown mechanism across the chromatophore double envelope membranes. Chromatophore-targeted proteins fall into two classes. Proteins exceeding 250 amino acids carry a conserved N-terminal sequence extension, termed the ‘chromatophore transit peptide’ (crTP), that is presumably involved in guiding these proteins into the chromatophore. Short imported proteins do not carry discernable targeting signals. To explore whether the import of protein is accompanied by their N-terminal processing, here we used a mass spectrometry-based approach to determine protein N-termini in Paulinella chromatophora and identified N-termini of 208 chromatophore-localized proteins. Our study revealed extensive N-terminal modifications by acetylation and proteolytic processing in both, the nucleus and chromatophore-encoded fraction of the chromatophore proteome. Mature N-termini of 37 crTP-carrying proteins were identified, of which 30 were cleaved in a common processing region. Our results imply that the crTP mediates trafficking through the Golgi, is bipartite and surprisingly only the N-terminal third (‘part 1’) becomes cleaved upon import, whereas the rest (‘part 2’) remains at the mature proteins. In contrast, short imported proteins remain largely unprocessed. Finally, this work sheds light on N-terminal processing of proteins encoded in an evolutionary-early-stage photosynthetic organelle and suggests host-derived post-translationally acting factors involved in dynamic regulation of the chromatophore-encoded chromatophore proteome.

INSTRUMENT(S): maXis

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Photosynthetic Cell

SUBMITTER: Pitter Huesgen

LAB HEAD: Pitter Huesgen

PROVIDER: PXD028527 | Pride | 2023-04-06

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	200505_Linda_SP3H_A_RH2_1_58.d.7z	Other
	200505_Linda_SP3H_B_RH3_1_59.d.7z	Other
	200505_Linda_SP3H_C_RH4_1_60.d.7z	Other
	200508_Linda_SP3H_A_RH2_1_77.d.7z	Other
	200508_Linda_SP3H_B_RH3_1_78.d.7z	Other

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Publications

A bipartite chromatophore transit peptide and N-terminal protein processing in the Paulinella chromatophore.

Oberleitner Linda L Perrar Andreas A Macorano Luis L Huesgen Pitter F PF Nowack Eva C M ECM

Plant physiology 20220501 1

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 pept ...[more]

PMID: 35043947

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