Protein Engineering vol. 16 no. 11 pp. 847-851, 2003
© 2003 Oxford University Press
Structural diversity in the small heat shock protein superfamily: control of aggregation by the N-terminal region
Center for Biophysics and Department of Biology, Rensselaer Polytechnic Institute, Science Center, Troy, NY 12180-3590, USA
1 To whom correspondence should be addressed. e-mail: salerj{at}rpi.edu
The small heat shock protein superfamily, extending over all kingdoms, is characterized by a common core domain with variable N- and C-terminal extensions. The relatively hydrophobic N-terminus plays a critical role in promoting and controlling high-order aggregation, accounting for the high degree of structural variability within the superfamily. The effects of N-terminal volume on aggregation were studied using chimeric and truncated proteins. Proteins lacking the N-terminal region did not aggregate above the tetramers, whereas larger N-termini resulted in large aggregates, consistent with the N-termini packing inside the aggregates. Variation in an extended internal loop differentiates typical prokaryotic and plant superfamily members from their animal counterparts; this implies different geometry in the dimeric building block of high-order aggregates.
Received March 15, 2003; revised May 20, 2003; accepted September 4, 2003.