Identification of functional residues essential for dehalogenation by the non-stereospecific α-haloalkanoic acid dehalogenase from Rhizobium sp. RC1

Abdul Hamid, Azzmer Azzar and Tengku Abdul Hamid, Tengku Haziyamin and Abdul Wahab, Roswanira and Huyop, Fahrul Zaman (2013) Identification of functional residues essential for dehalogenation by the non-stereospecific α-haloalkanoic acid dehalogenase from Rhizobium sp. RC1. Journal of Basic Microbiology, 53. pp. 1-7. ISSN 0233-111X (Print) 1521-4028 (Online)

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Abstract

The non-stereospecific α-haloalkanoic acid dehalogenase DehE from Rhizobium sp. RC1 catalyzes the removal of the halide from α-haloalkanoic acid D,L-stereoisomers and, by doing so, converts them into hydroxyalkanoic acid L,D-stereoisomers, respectively. DehE has been extensively studied to determine its potential to act as a bioremediation agent, but its structure/function relationship has not been characterized. For this study, we explored the functional relevance of several putative active-site amino acids by site-specific mutagenesis. Ten active-site residues were mutated individually, and the dehalogenase activity of each of the 10 resulting mutants in soluble cell lysates against D- and L-2-chloropropionic acid was assessed. Interestingly, the mutants W34 → A, F37 → A, and S188 → A had diminished activity, suggesting that these residues are functionally relevant. Notably, the D189 → N mutant had no activity, which strongly implies that it is a catalytically important residue. Given our data, we propose a dehalogenation mechanism for DehE, which is the same as that suggested for other non-stereospecific α-haloalkanoic acid dehalogenases. To the best of our knowledge, this is the first report detailing a functional aspect for DehE, and our results could help pave the way for the bioengineering of haloalkanoic acid dehalogenases with improved catalytic properties

Item Type:	Article (Journal)
Additional Information:	4261/33817
Uncontrolled Keywords:	Active-site; DehE; Haloalkanoic acid; Non-stereospecific dehalogenase; Site-directed mutagenesis
Subjects:	Q Science > Q Science (General)
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Science > Department of Biotechnology
Depositing User:	Dr Tengku Haziyamin Tengku Abd Hamid
Date Deposited:	23 Jan 2014 13:07
Last Modified:	27 Nov 2014 16:43
URI:	http://irep.iium.edu.my/id/eprint/33817

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