Van Wyk, Stefan GeorgeKunert, Karl J.Cullis, C.A. (Christoper Ashley)Pillay, PriyenMakgopa, Matome EugeneSchluter, UrteVorster, Barend Juan2016-04-262016-05Van Wyk, SG, Kunert, KJ, Cullis, CA, Pillay, P, Makgopa, ME, Schlüter, U & Vorster, BJ 2016, 'Review : the future of cystatin engineering', Plant Science, vol. 246., pp. 119-127.0168-9452 (print)1873-2259 (online)10.1016/j.plantsci.2016.02.016http://hdl.handle.net/2263/52166Plant cystatins are naturally occurring protease inhibitors that prevent proteolysis by papain-like cysteine proteases. Their protective action against environmental stresses has been relatively well characterised. Still, there is a need to greatly improve both potency and specificity based on the current rather poor performance of cystatins in biotechnological applications. Research in creating more potent and specific cystatins, including amino acid substitutions in either conserved cystatin motifs and/or at variable amino acid sites, is reviewed. Existing gaps for better understanding of cystatin-protease interactions are further explored. Current knowledge on multi-cystatins or hybrid protease inhibitors involving cystatins as an additional option for cystatin engineering is further outlined along with the nuances of how cystatins with rather unusual amino acid sequences might actually help in cystatin engineering. Finally, future opportunities for application of cystatins are highlighted which include applications in genetically modified transgenic plants for environmental stress protection and also as nutraceuticals, as part of more nutritious food. Further opportunities might also include the possible management of diseases and disorders, often associated with lifestyle changes, and the most immediate and promising application which is inclusion into plant-based recombinant protein production platforms.en© 2016 Elsevier Ireland Ltd. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Plant Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Plant Science, vol. 246, pp. 119-127, 2016. doi : 10.1016/j.plantsci.2016.02.016.CystatinPlantCystatin engineeringMulti-cystatinsPhytocystatinProtease inhibitorProteolysisPostprint Article