PMID- 33097503
OWN - NLM
STAT- MEDLINE
DCOM- 20210322
LR  - 20210618
IS  - 1098-5336 (Electronic)
IS  - 0099-2240 (Print)
IS  - 0099-2240 (Linking)
VI  - 87
IP  - 1
DP  - 2020 Dec 17
TI  - Hexachlorobenzene Monooxygenase Substrate Selectivity and Catalysis: Structural 
      and Biochemical Insights.
LID - 10.1128/AEM.01965-20 [doi]
LID - e01965-20
AB  - Hexachlorobenzene (HCB), as one of the persistent organic pollutants (POPs) and a 
      possible human carcinogen, is especially resistant to biodegradation. In this 
      study, HcbA1A3, a distinct flavin-N5-peroxide-utilizing enzyme and the sole known 
      naturally occurring aerobic HCB dechlorinase, was biochemically characterized. 
      Its apparent preference for HCB in binding affinity revealed that HcbA1 could 
      oxidize only HCB rather than less-chlorinated benzenes such as pentachlorobenzene 
      and tetrachlorobenzenes. In addition, the crystal structure of HcbA1 and its 
      complex with flavin mononucleotide (FMN) were resolved, revealing HcbA1 to be a 
      new member of the bacterial luciferase-like family. A much smaller 
      substrate-binding pocket of HcbA1 than is seen with its close homologues suggests 
      a requirement of limited space for catalysis. In the active center, Tyr362 and 
      Asp315 are necessary in maintaining the normal conformation of HcbA1, while 
      Arg311, Arg314, Phe10, Val59, and Met12 are pivotal for the substrate affinity. 
      They are supposed to place HCB at a productive orientation through multiple 
      interactions. His17, with its close contact with the site of oxidation of HCB, 
      probably fixes the target chlorine atom and stabilizes reaction intermediates. 
      The enzymatic characteristics and crystal structures reported here provide new 
      insights into the substrate specificity and catalytic mechanism of HcbA1, which 
      paves the way for its rational engineering and application in the bioremediation 
      of HCB-polluted environments.IMPORTANCE As an endocrine disrupter and possible 
      carcinogen to human beings, hexachlorobenzene (HCB) is especially resistant to 
      biodegradation, largely due to difficulty in its dechlorination. The lack of 
      knowledge of HCB dechlorinases limits their application in bioremediation. 
      Recently, an HCB monooxygenase, HcbA1A3, representing the only naturally 
      occurring aerobic HCB dechlorinase known so far, was reported. Here, we report 
      its biochemical and structural characterization, providing new insights into its 
      substrate selectivity and catalytic mechanism. This research also increases our 
      understanding of HCB dechlorinases and flavin-N5-peroxide-utilizing enzymes.
CI  - Copyright (c) 2020 American Society for Microbiology.
FAU - Guo, Yuan
AU  - Guo Y
AD  - State Key Laboratory of Microbial Metabolism, School of Life Sciences and 
      Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
AD  - Joint International Research Laboratory of Metabolic & Developmental Sciences, 
      Shanghai Jiao Tong University, Shanghai, China.
FAU - Li, De-Feng
AU  - Li DF
AUID- ORCID: 0000-0002-8683-019X
AD  - State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese 
      Academy of Sciences, Beijing, China.
FAU - Ji, Huining
AU  - Ji H
AD  - State Key Laboratory of Microbial Metabolism, School of Life Sciences and 
      Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
AD  - Joint International Research Laboratory of Metabolic & Developmental Sciences, 
      Shanghai Jiao Tong University, Shanghai, China.
FAU - Zheng, Jianting
AU  - Zheng J
AD  - State Key Laboratory of Microbial Metabolism, School of Life Sciences and 
      Biotechnology, Shanghai Jiao Tong University, Shanghai, China jtzheng@sjtu.edu.cn 
      ningyi.zhou@sjtu.edu.cn.
AD  - Joint International Research Laboratory of Metabolic & Developmental Sciences, 
      Shanghai Jiao Tong University, Shanghai, China.
FAU - Zhou, Ning-Yi
AU  - Zhou NY
AUID- ORCID: 0000-0002-0917-5750
AD  - State Key Laboratory of Microbial Metabolism, School of Life Sciences and 
      Biotechnology, Shanghai Jiao Tong University, Shanghai, China jtzheng@sjtu.edu.cn 
      ningyi.zhou@sjtu.edu.cn.
AD  - Joint International Research Laboratory of Metabolic & Developmental Sciences, 
      Shanghai Jiao Tong University, Shanghai, China.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20201217
PL  - United States
TA  - Appl Environ Microbiol
JT  - Applied and environmental microbiology
JID - 7605801
RN  - 0 (Bacterial Proteins)
RN  - 4Z87H0LKUY (Hexachlorobenzene)
RN  - EC 1.- (Mixed Function Oxygenases)
SB  - IM
MH  - Bacterial Proteins/*metabolism
MH  - Catalysis
MH  - Escherichia coli/enzymology
MH  - Hexachlorobenzene/*metabolism
MH  - Microorganisms, Genetically-Modified/enzymology
MH  - Mixed Function Oxygenases/*metabolism
MH  - Nocardioides/*enzymology
MH  - Substrate Specificity
PMC - PMC7755259
OTO - NOTNLM
OT  - biodegradation
OT  - catalytic mechanism
OT  - crystal structure
OT  - dechlorinase
OT  - flavin-N5-peroxide
OT  - hexachlorobenzene
OT  - monooxygenase
EDAT- 2020/10/25 06:00
MHDA- 2021/03/23 06:00
PMCR- 2021/06/17
CRDT- 2020/10/24 05:28
PHST- 2020/08/10 00:00 [received]
PHST- 2020/10/14 00:00 [accepted]
PHST- 2020/10/25 06:00 [pubmed]
PHST- 2021/03/23 06:00 [medline]
PHST- 2020/10/24 05:28 [entrez]
PHST- 2021/06/17 00:00 [pmc-release]
AID - AEM.01965-20 [pii]
AID - 01965-20 [pii]
AID - 10.1128/AEM.01965-20 [doi]
PST - epublish
SO  - Appl Environ Microbiol. 2020 Dec 17;87(1):e01965-20. doi: 10.1128/AEM.01965-20. 
      Print 2020 Dec 17.