The importance of the 5’<em>rbc</em>L coding sequence for co-translational processing and biogenesis of tobacco Rubisco. — ASN Events
  1. Schedule
  2. Session Seven - Poster Session B includes Happy Hour & Trade Display
  3. The importance of the 5’rbcL coding sequence for co-translational processing and biogenesis of tobacco Rubisco.

The importance of the 5’rbcL coding sequence for co-translational processing and biogenesis of tobacco Rubisco. (#240)

Douglas Orr 1 , Rosemary Birch 1 , Lynnette Dirk 2 , Robert Houtz 2 , Spencer Whitney 1
  1. Plant Sciences Division, Research School of Biology, The Australian National University, Canberra, ACT, Australia
  2. Department of Horticulture, University of Kentucky, Lexington, Kentucky, USA

The importance of Rubisco as the ‘gateway’ enzyme for carbon entry into the biosphere, and its inherently flawed catalytic properties, have made it a popular target for improvement as a step towards enhancing photosynthesis and agricultural yields. Significant attention continues to be devoted to improving our understanding of sequence-performance relationships among catalytically diverse Rubisco isoforms in the hope of engineering improvements to Rubisco into crops. Critical to such goals is to fully understand the cellular requirements needed for Rubisco biogenesis.

Of the many processes involved in protein biogenesis and function are often a myriad of co- and post-translational processing events. For Rubisco in plants both its chloroplast genome (plastome) encoded large subunits (LSu) and nuclear encoded, cytosolic made small subunits (SSu) undergo N-terminal co- and post-translational modification (PTMs) both prior to, during and (possibly) following their assembly into hexadecameric (L8S8) complexes within the chloroplast stroma. The highly conserved N-terminal amino acid sequence of plant LSu’s undergoes a number of co- and post-translational modifications that result in the excision of Met-1 and Ser-2 and acetylation of the mature N-terminal Pro-3. A functional significance for this conserved co-translational processing remains undefined. To address this question we have generated a range of transplastomic tobacco lines incorporating targeted changes to the 5’rbcL coding sequence. Specific mutations to the Ser-2 and Pro-3 codons have been introduced into the rbcL gene LSu codon that have led to changes in L-subunit processing.

Presented will be data on the transplastomic tobacco LSu mutant lines made, including the effects of the Ser-2 and Pro-3 substitutions on N-terminal processing and translation of the LSu and the corresponding influence the changes have on Rubisco biogenesis and plant growth. These findings provide new insight into the putative series of LSu processing events in plastids and areas for future consideration and testing.