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Cry Protein Crystal-Immobilized Metallothioneins for Bioremediation of Heavy Metals from Water

School of Life Sciences and Center of Novel Biomaterials, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
Authors to whom correspondence should be addressed.
Crystals 2019, 9(6), 287;
Received: 8 May 2019 / Revised: 27 May 2019 / Accepted: 30 May 2019 / Published: 1 June 2019
(This article belongs to the Special Issue Biological Crystallization)
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Cry proteins have been the subject of intense research due to their ability to form crystals naturally in Bacillus thuringiensis (Bt). In this research we developed a new strategy that allows for the removal of cadmium and chromium from wastewater by using one Cry protein, Cry3Aa, as a framework to immobilize tandem repeats of the cyanobacterial metallothionein SmtA from Synechococcus elongatus (strain PCC 7942). SmtA is a low molecular weight cysteine-rich protein known to bind heavy metals. A series of Cry3Aa-SmtA constructs were produced by the fusion of one, three, or six tandem repeats of SmtA to Cry3Aa. Overexpression of these constructs in Bt resulted in the production of pure Cry3Aa-SmtA fusion crystals that exhibited similar size, crystallinity, and morphology to that of native Cry3Aa protein crystals. All three Cry3Aa-SmtA constructs exhibited efficient binding to cadmium and chromium, with the binding capacity correlated with increasing SmtA copy number. These results suggest the potential use of Cry3Aa-SmtA crystals as a novel biodegradable and cost-effective approach to the removal of toxic heavy metals from the environment. View Full-Text
Keywords: Cry protein crystals; metallothioneins; bioremediation; heavy metal contamination Cry protein crystals; metallothioneins; bioremediation; heavy metal contamination

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Sun, Q.; Cheng, S.W.; Cheung, K.; Lee, M.M.; Chan, M.K. Cry Protein Crystal-Immobilized Metallothioneins for Bioremediation of Heavy Metals from Water. Crystals 2019, 9, 287.

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