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ER membrane-localized oxidoreductase Ero1 is required for disulfide bond formation in the rice endosperm.

ABSTRACT: The developing endosperm of rice (Oryza sativa, Os) synthesizes a large amount of storage proteins on the rough (r)ER. The major storage proteins, glutelins and prolamins, contain either intra or intermolecular disulfide bonds, and oxidative protein folding is necessary for the sorting of the proteins to the protein bodies. Here, we investigated an electron transfer pathway for the formation of protein disulfide bonds in the rER of the rice endosperm, focusing on the roles of the thiol-disulfide oxidoreductase, OsEro1. Confocal microscopic analysis revealed that N-glycosylated OsEro1 is localized to the rER membrane in the subaleurone cells, and that targeting of OsEro1 to the rER membrane depends on the N-terminal region from Met-1 to Ser-55. The RNAi knockdown of OsERO1 inhibited the formation of native disulfide bonds in the glutelin precursors (proglutelins) and promoted aggregation of the proglutelins through nonnative intermolecular disulfide bonds in the rER. Inhibition of the formation of native disulfide bonds was also observed in the seeds of the esp2 mutant, which lacks protein disulfide isomerase-like (PDIL)1;1, but shows enhanced OsEro1 expression. We detected the generation of H(2)O(2) in the rER of the WT subaleurone cells, whereas the rER-derived H(2)O(2) levels decreased markedly in EM49 homozygous mutant seeds, which have fewer sulfhydryl groups than the WT seeds. Together, we propose that the formation of native disulfide bonds in proglutelins depends on an electron transfer pathway involving OsEro1 and OsPDIL.

SUBMITTER: Onda Y

PROVIDER: S-EPMC2729036 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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ER membrane-localized oxidoreductase Ero1 is required for disulfide bond formation in the rice endosperm.

Onda Yayoi Y Kumamaru Toshihiro T Kawagoe Yasushi Y

Proceedings of the National Academy of Sciences of the United States of America 20090806 33

The developing endosperm of rice (Oryza sativa, Os) synthesizes a large amount of storage proteins on the rough (r)ER. The major storage proteins, glutelins and prolamins, contain either intra or intermolecular disulfide bonds, and oxidative protein folding is necessary for the sorting of the proteins to the protein bodies. Here, we investigated an electron transfer pathway for the formation of protein disulfide bonds in the rER of the rice endosperm, focusing on the roles of the thiol-disulfide ...[more]

PMID: 19666483

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Project description:Chlamydia trachomatis is an obligate intracellular bacterium with a distinctive biphasic developmental cycle that alternates between two distinct cell types; the extracellular infectious elementary body (EB) and the intracellular replicating reticulate body (RB). Members of the genus Chlamydia are dependent on the formation and degradation of protein disulfide bonds. Moreover, disulfide cross-linking of EB envelope proteins is critical for the infection phase of the developmental cycle. We have identified in C. trachomatis a homologue of the Disulfide Bond forming membrane protein Escherichia coli (E. coli) DsbB (hereafter named CtDsbB) and-using recombinant purified proteins-demonstrated that it is the redox partner of the previously characterised periplasmic oxidase C. trachomatis Disulfide Bond protein A (CtDsbA). CtDsbA protein was detected in C. trachomatis inclusion vacuoles at 20 h post infection, with more detected at 32 and similar levels at 44 h post infection as the developmental cycle proceeds. As a redox pair, CtDsbA and CtDsbB largely resemble their homologous counterparts in E. coli; CtDsbA is directly oxidised by CtDsbB, in a reaction in which both periplasmic cysteine pairs of CtDsbB are required for complete activity. In our hands, this reaction is slow relative to that observed for E. coli equivalents, although this may reflect a non-native expression system and use of a surrogate quinone cofactor. CtDsbA has a second non-catalytic disulfide bond, which has a small stabilising effect on the protein's thermal stability, but which does not appear to influence the interaction of CtDsbA with its partner protein CtDsbB. Expression of CtDsbA during the RB replicative phase and during RB to EB differentiation coincided with the oxidation of the chlamydial outer membrane complex (COMC). Together with our demonstration of an active redox pairing, our findings suggest a potential role for CtDsbA and CtDsbB in the critical disulfide bond formation step in the highly regulated development cycle.

Dataset Information

ER membrane-localized oxidoreductase Ero1 is required for disulfide bond formation in the rice endosperm.

Publications

ER membrane-localized oxidoreductase Ero1 is required for disulfide bond formation in the rice endosperm.

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