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Publication Abstract from PubMed

Subtilases are serine proteases found in Archae, Bacteria, yeasts, and higher eukaryotes. Plants possess many more of these subtilisin-like endopeptidases than animals, e.g., 56 identified genes in Arabidopsis compared with only 9 in humans, indicating important roles for subtilases in plant biology. We report the first structure of a plant subtilase, SBT3 from tomato, in the active apo form and complexed with a chloromethylketone (cmk) inhibitor. The domain architecture comprises an N-terminal protease domain displaying a 132 aa protease-associated (PA) domain insertion and a C-terminal seven-stranded jelly-roll fibronectin (Fn) III-like domain. We present the first structural evidence for an explicit function of PA domains in proteases revealing a vital role in the homo-dimerization of SBT3 and in enzyme activation. Although Ca(2+)-binding sites are conserved and critical for stability in other subtilases, SBT3 was found to be Ca(2+)-free and its thermo stability is Ca(2+)-independent.

Structural basis for Ca2+-independence and activation by homodimerization of tomato subtilase 3.,Ottmann C, Rose R, Huttenlocher F, Cedzich A, Hauske P, Kaiser M, Huber R, Schaller A Proc Natl Acad Sci U S A. 2009 Oct 6;106(40):17223-8. Epub 2009 Sep 23. PMID:19805099^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.