The gene for the ribulose-1,5-bisphosphate carboxylase/ oxygenase (Rubisco) small subunit relocated to the plastid genome of tobacco directs the synthesis of small subunits that assemble into Rubisco

S. M. Whitney, T. John Andrews*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    81 Citations (Scopus)

    Abstract

    To assess the extent to which a nuclear gene for a chloroplast protein retained the ability to be expressed in its presumed preendosymbiotic location, we relocated the RbcS gene for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to the tobacco plastid genome. Plastid RbcS transgenes, both with and without the transit presequence, were equipped with 3′ hepta-histidine - encoding sequences and psbA promoter and terminator elements. Both transgenes were transcribed abundantly, and their products were translated into small subunit polypeptides that folded correctly and assembled into the Rubisco hexadecamer. When present, either the transit presequence was not translated or the transit peptide was cleaved completely. After assembly into Rubisco, transplastomic small subunits were relatively stable. The hepta-histidine sequence fused to the C terminus of a single small subunit was sufficient for isolation of the whole Rubisco hexadecamer by Ni2+ chelation. Small subunits produced by the plastid transgenes were not abundant, never exceeding ∼1% of the total small subunits, and they differed from cytoplasmically synthesized small subunits in their N-terminal modifications. The scarcity of transplastomic small subunits might be caused by inefficient translation or assembly.

    Original languageEnglish
    Pages (from-to)193-205
    Number of pages13
    JournalPlant Cell
    Volume13
    Issue number1
    DOIs
    Publication statusPublished - 2001

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