JXB Advance Access originally published online on March 18, 2008
Journal of Experimental Botany 2008 59(7):1635-1645; doi:10.1093/jxb/erm360
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SPECIAL ISSUE REVIEW PAPER |
Co- and post-translational modifications in Rubisco: unanswered questions
Department of Horticulture, Plant Physiology/Biochemistry/Molecular Biology Program, University of Kentucky, 1405 Veterans Drive, 441 Plant Science Building, Lexington, KY 40546-0312, USA
* To whom correspondence should be addressed. E-mail: rhoutz{at}uky.edu
Both the large (LS) and small (SS) subunits of Rubisco are subject to a plethora of co- and post-translational modifications. With the exceptions of LS carbamylation and SS transit sequence processing, the remaining modifications, including deformylation, acetylation, methylation, and N-terminal proteolytic processing of the LS, are still biochemically and/or functionally undefined although they are found in nearly all forms of Rubisco from vascular plants. A collection of relatively unique enzymes catalyse these modifications, and several have been characterized in other organisms. Some of the observed modifications in the LS and SS clearly suggest novel changes in enzyme specificity and/or activity, and others have common features with other co- and post-translationally modifying enzymes. With the possible exception of Lys14 methylation in the LS, processing of both the LS and SS of Rubisco is by default an ordered process sequentially leading up to the final forms observed in the holoenzyme. An overview of the nature of structural modifications in the LS and SS of Rubisco is presented, and, where possible, the nature of the enzymes catalysing these modifications (either through similarity with other known enzymes or through direct enzymological characterization) is described. Overall, there are a distinct lack of functional and mechanistic observations for modifications in Rubisco and thus represent many potentially productive avenues for research.
Key words:
Co-translational processing, dipeptidase, 
N-methyltransferase, methionine aminopeptidase, N
-acetyltransferase, peptide deformylase, post-translational processing, Rubisco, stromal processing peptidase
Received 3 October 2007; Revised 30 November 2007 Accepted 18 December 2007