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Acta Cryst. (2014). A70, C441
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Trehalose synthase (TreS) catalyzes the reversible conversion of maltose to trehalose in mycobacteria as one of three biosynthetic pathways to this non-reducing disaccharide. Given the importance of trehalose to survival of mycobacteria there has been considerable interest in understanding the enzymes involved in its production; indeed the structures of the key enzymes in the other two pathways have already been determined. Herein we present the first structure of TreS from Mycobacterium smegmatis, thereby providing insights into the catalytic machinery involved in this intriguing intramolecular reaction. This structure, which is of interest both mechanistically and as a potential pharmaceutical target, reveals a narrow and enclosed active site cleft within which the intramolecular rearrangement can occur with minimal hydrolysis. We also present the structure of a complex of TreS with acarbose, revealing a hitherto unsuspected oligosaccharide binding site within the C-terminal domain. This may well provide an anchor point for the association of TreS with glycogen, thereby enhancing its role in glycogen biosynthesis and degradation.

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Acta Cryst. (2014). A70, C804
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Human heat shock protein 27 (Hsp27) is an oligomeric and cell survival protein that has been associated with several cancers including prostrate and breast cancer. It's a known anti-apoptotic protein that functions as a molecular chaperone for several proteins. Hsp27 characteristically binds and stabilizes numerous partially unfolded proteins preventing their degradation, and has been shown to prevent actin polymerization in vitro. Several actin-binding residues involved in this interaction have been identified at the N-terminal loop and highly conserved alpha crystallin domains of Hsp27. Multiple assays have demonstrated that this hydrophobic actin-binding site is also involved in other protein binding. We therefore propose a common substrate-binding region on Hsp27 and present a model of Hsp27 binding to actin.
Keywords: Hsp27; Actin; crystallin.
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