Biochemical Characterization of a Haloalkane Dehalogenase DadB from Alcanivorax dieselolei B-5

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	Biochemical Characterization of a Haloalkane Dehalogenase DadB from Alcanivorax dieselolei B-5
	Li, Anzhang ; Shao, Zongze ; Li AZ(李安章)
刊名	http://dx.doi.org/10.1371/journal.pone.0089144
	2014-02-28
关键词	SPHINGOMONAS-PAUCIMOBILIS UT26 XANTHOBACTER-AUTOTROPHICUS GJ10 BRADYRHIZOBIUM-JAPONICUM DEGRADING BACTERIUM CRYSTAL-STRUCTURE PURIFICATION GENE EXPRESSION EVOLUTION SUBSTRATE
英文摘要	National Science Foundation of China [41176154]; Public Welfare Project of SOA [201005032]; COMRA project [DY125-15-R-01]; International Sci & Tech Cooperation Program of China [2010DFB23320]; Recently, we found that Alcanivorax bacteria from various marine environments were capable of degrading halogenated alkanes. Genome sequencing of A. dieselolei B-5 revealed two putative haloalkane dehalogenase (HLD) genes, which were supposed to be involved in degradation of halogenated compounds. In this report, we confirm for the first time that the Alcanivorax bacterium encodes a truly functional HLD named DadB. An activity assay with 46 halogenated substrates indicated that DadB possesses broad substrate range and has the highest overall activity among the identified HLDs. DadB prefers brominated substrates; chlorinated alkenes; and the C-2-C-3 substrates, including the persistent pollutants of 1, 2-dichloroethane, 1,2-dichloropropane and 1,2,3-trichloropropane. As DadB displays no detectable activity toward long-chain haloalkanes such as 1-chlorohexadecane and 1-chlorooctadecane, the degradation of them in A. dieselolei B-5 might be attributed to other enzymes. Kinetic constants were determined with 6 substrates. DadB has highest affinity and largest k(cat)/K-m value toward 1,3-dibromopropane (K-m = 0.82 mM, k(cat)/K-m = 16.43 mM(-1).s(-1)). DadB aggregates fast in the buffers with pH <= 7.0, while keeps stable in monomer form when pH >= 7.5. According to homology modeling, DadB has an open active cavity with a large access tunnel, which is supposed important for larger molecules as opposed to C-2-C-3 substrates. Combined with the results for other HLDs, we deduce that residue I247 plays an important role in substrate selection. These results suggest that DadB and its host, A. dieselolei B-5, are of potential use for biocatalysis and bioremediation applications.
语种	英语
出版者	PUBLIC LIBRARY SCIENCE
内容类型	期刊论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/90827]
专题	生命科学－已发表论文
推荐引用方式 GB/T 7714	Li, Anzhang,Shao, Zongze,Li AZ. Biochemical Characterization of a Haloalkane Dehalogenase DadB from Alcanivorax dieselolei B-5[J]. http://dx.doi.org/10.1371/journal.pone.0089144,2014.
APA	Li, Anzhang,Shao, Zongze,&李安章.(2014).Biochemical Characterization of a Haloalkane Dehalogenase DadB from Alcanivorax dieselolei B-5.http://dx.doi.org/10.1371/journal.pone.0089144.
MLA	Li, Anzhang,et al."Biochemical Characterization of a Haloalkane Dehalogenase DadB from Alcanivorax dieselolei B-5".http://dx.doi.org/10.1371/journal.pone.0089144 (2014).