Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2008
Publication Date: 6/23/2008
Citation: Schwarz, E.M., Ort, D.R. 2008. Chlorophyll allocation during chloroplast development and repair [abstract]. American Society of Plant Biologists Annual Meeting. Paper No. P20007. Available: http://abstracts.aspb.org/pb2008/public/P20/P20007.html. Interpretive Summary:
Technical Abstract: Photosynthetic plasticity is well known to be a crucial aspect of plant survival in changing conditions. The molecular mechanisms involved in the regulation of the light harvesting antenna complexes in response to a dynamic light environment and the turnover and repair of the PSII core complex due to unavoidable photodamage have been the subject of intense scrutiny. However, the integration of chlorophyll metabolism and transport into these processes remains poorly understood. Specifically, it is unclear whether chlorophyll is degraded concomitantly with the degradation of its binding protein. Evidence suggests that chlorophyll may instead by recycled and repackaged with different binding proteins. To investigate this hypothesis we have developed an in-vitro biosynthesis of 14C Aminolevulinate from 14C Glycine, allowing sufficiently strong in-vivo radiolabeling of chlorophyll for visualization of chlorophyll/protein complexes in native green gels. Initial studies reveal that under steady state conditions mature leaves incorporate newly synthesized chlorophyll entirely into LHC trimers, whereas chlorophyll is distributed throughout the photosynthetic apparatus during active growth. Exposure of plants with LHC complexes containing labeled chlorophyll to high light conditions results in redistribution of some of this label to other thylakoid complexes, and may result in the formation of high molecular weight complexes. Further research using tagged proteins will be necessary to determine whether the redistribution of labeled chlorophyll results from chlorophyll repackaging or protein complex rearrangement.