Comparative Algal and Byrophyte Physiology
Waters, Elizabeth, R .
Comparative Genomic Analysis of the Heat Shock Proteins.
The heat shock proteins or HSPs are found in all organisms. HSPs are a crucial part of the heat shock response, which allows organisms to withstand exposure to high temperature stress. Most HSPs are chaperones, i.e., they assist in the folding of other proteins. The individual HSP families (for example the HSP20s, HSP70s, and HSP100s) are not related to each other. However, progress in molecular studies now shows us that during protein folding there are complex interactions among the various HSPs, indicating that these proteins to some extent need to evolve together. While the flowering plants share HSP homologs with other eukaryotes, as well as with bacteria and archaea, it is clear that the flowering plant HSPs and heat shock response vary considerably from their animal and fungal homologs. It has been proposed that the challenges of life on land may have been a very important selective pressure in driving the evolution of the HSPs, however until now this proposal has been difficult in evaluate. The recent sequencing of the genomes of five “algal” photosynthetic eukaryotes: Thalassiosira pseudonana, Cyanidioschyzon merolae, Chlamydomonas reinhardtii Ostreococcus lucimarinus and Ostreococcus tauri now makes possible comparative genomic analysis of “algal” heat shock proteins with land plant homologs. I have examined the evolution of three major HSP families: HSP100, HSP70 and HSP20. My analysis indicates that these families have had very different evolutionary histories. For example each contains homologs found in both the chloroplast and mitochondria but the origins and histories of these organelle proteins are different in each family. Despite these differences it is also clear that diversification within each family has occurred between the divergence of chlorophyte green algae and the origin of land plants. Further, it appears that the types of protein divergence is different in each HSP family
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1 - San Diego State University, Biology, 5500 Campanile Drive, San Diego, CA, 92182, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 4/Hilton
Date: Tuesday, July 10th, 2007
Time: 9:00 AM