Cell Stress and Chaperones

, Volume 13, Issue 2, pp 127–142

Comparative analysis of the small heat shock proteins in three angiosperm genomes identifies new subfamilies and reveals diverse evolutionary patterns

  • Elizabeth R. Waters
  • Brian D. Aevermann
  • Zipporah Sanders-Reed
Original paper

DOI: 10.1007/s12192-008-0023-7

Cite this article as:
Waters, E.R., Aevermann, B.D. & Sanders-Reed, Z. Cell Stress and Chaperones (2008) 13: 127. doi:10.1007/s12192-008-0023-7


The small heat shock proteins (sHSPs) are a diverse family of molecular chaperones. It is well established that these proteins are crucial components of the plant heat shock response. They also have important roles in other stress responses and in normal development. We have conducted a comparative sequence analysis of the sHSPs in three complete angiosperms genomes: Arabidopsis thaliana, Populus trichocarpa, and Oryza sativa. Our phylogenetic analysis has identified four additional plant sHSP subfamilies and thus has increased the number of plant sHSP subfamilies from 7 to 11. We have also identified a number of novel sHSP genes in each genome that lack close homologs in other genomes. Using publicly available gene expression data and predicted secondary structures, we have determined that the sHSPs in plants are far more diverse in sequence, expression profile, and in structure than had been previously known. Some of the newly identified subfamilies are not stress regulated, may not posses the highly conserved large oligomer structure, and may not even function as molecular chaperones. We found no consistent evolutionary patterns across the three species studied. For example, gene conversion was found among the sHSPs in O. sativa but not in A. thaliana or P. trichocarpa. Among the three species, P. trichocarpa had the most sHSPs. This was due to an expansion of the cytosolic I sHSPs that was not seen in the other two species. Our analysis indicates that the sHSPs are a dynamic protein family in angiosperms with unexpected levels of diversity.

Supplementary material

12192_2008_23_MOESM1_ESM.doc (68 kb)
Supplementary Fig. 1Alignment of sHSP amino acid sequences (DOC 67.5 KB)
12192_2008_23_MOESM2_ESM.doc (67 kb)
Supplementary Fig. 2–4A. thaliana cytosolic I DNA alignment (DOC 67.0 KB)
12192_2008_23_MOESM3_ESM.doc (118 kb)
Supplementary Table 1Synonymous (Ks) and Nonsynonymous substitutions for the Cytosolic I genes (DOC 118 KB)

Copyright information

© Cell Stress Society International 2008

Authors and Affiliations

  • Elizabeth R. Waters
    • 1
  • Brian D. Aevermann
    • 1
  • Zipporah Sanders-Reed
    • 1
  1. 1.Department of BiologySan Diego State UniversitySan DiegoUSA

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