Structural basis for Ca2+-independence and activation by homodimerization of tomato subtilase 3

C. Ottmann, R. Rose, F. Huttenlocher, A. Cedzich, P. Hauske, M. Kaiser, R. Huber, A. Schaller

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60 Citations (Scopus)
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Abstract

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 Ca2+-binding sites are conserved and critical for stability in other subtilases, SBT3 was found to be Ca2+-free and its thermo stability is Ca2+-independent.
Original languageEnglish
Pages (from-to)17223-17228
JournalProceedings of the National Academy of Sciences of the United States of America (PNAS)
Volume106
Issue number40
DOIs
Publication statusPublished - 2009

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