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Title: MECHANISM OF LIGHT REGULATION OF RUBISCO: A UNIQUE ROLE FOR THE LARGER RUBISCO ACTIVASE ISOFORM INVOLVING REDUCTIVE ACTIVATION BY THIOREDOXIN-F.

Author
item ZHANG, NING - PLANT BIO/CROP SCI UOFILL
item PORTIS JR, ARCHIE

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/1999
Publication Date: N/A
Citation: Zhang, N., Portis Jr, A.R. 1999. Mechanism of light regulation of rubisco: a unique role for the larger rubisco activase isoform involving reductive activation by thioredoxin-f.. Proceedings of the National Academy of Sciences. USA96:9438-9443.

Interpretive Summary:

Technical Abstract: The activity of Rubisco, the enzyme that captures carbon dioxide, often limits photosynthesis, the process by which plants use light energy from the sun to make carbohydrates for growth from carbon dioxide and water. In order to have activity, Rubisco requires modification by a process called activation, which is determined and hence regulated by another protein known as Rubisco activase. Rubisco activity might be increased to improve plant growth by altering the regulation of activation. Most plants contain two isoforms of Rubiso activase that are created by alternative splicing during gene transcription. In this study, we found that the activity of the larger isoform is increased by the reduction of two cysteine residues unique to this isoform via thioredoxin. However when combined, the activity of both isoforms could be regulated by reduction/oxidation. This new means of Rubisco regulation directly links the activity of Rubisco to the availability of reducing power provided by light absorption. This information will benefit scientists attempting to modify the properties and regulation of Rubisco in ways beneficial for increased photosynthesis by crop plants.