A marine viral halogenase that iodinates diverse substrates
Danai S Gkotsi1,2, Hannes Ludewig1,2, Sunil V Sharma1,2
1School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK.
Nature Chemistry
|October 16, 2019
Summary
Scientists characterized a viral halogenase (VirX1) from cyanophages. This enzyme regioselectively iodinates diverse substrates, offering potential insights into host metabolism and biocatalysis.
Area of Science:
- Microbiology
- Biochemistry
- Virology
Background:
- Oceanic cyanobacteria are vital oxygen producers and are infected by cyanophages.
- Cyanophages possess metabolic genes influencing host processes like photosynthesis and metabolism.
- Viral halogenases, previously linked to secondary metabolism, are increasingly recognized for their enzymatic roles.
Purpose of the Study:
- To characterize a novel flavin-dependent viral halogenase (VirX1) from a cyanophage.
- To investigate the substrate specificity and regioselectivity of VirX1, particularly its iodination capabilities.
- To explore the potential implications of VirX1 for host metabolism and its utility in biocatalysis.
Main Methods:
- Isolation and characterization of wild-type VirX1 from a cyanophage.
- Enzymatic assays to determine substrate range and regioselectivity.
- Kinetic analysis to quantify enzyme activity and substrate preference.
Main Results:
- VirX1 was identified as a flavin-dependent viral halogenase.
- VirX1 demonstrated regioselective halogenation across a diverse substrate range.
- A strong preference for forming aryl iodide species was observed, with significant catalytic efficiency.
Conclusions:
- VirX1 is the first reported flavin-dependent halogenase capable of in vitro iodination.
- The enzyme's broad substrate flexibility and iodination preference make it a valuable biocatalytic tool.
- VirX1 may play a role in the metabolism of its cyanophage host, impacting host biochemistry.
Related Concept Videos
01:28Multiple Halogenation of Methyl Ketones: Haloform Reaction
2.8K
A method involving the transformation of methyl ketones to carboxylic acids using excess base and halogen is called the haloform reaction. It begins with the deprotonation of α hydrogen to form an enolate ion which reacts with the electrophilic halogen to give an α-halo ketone. The step continues until all the α protons are substituted to form a trihalomethyl ketone. The resulting molecule is unstable, and in the presence of a hydroxide base, it readily undergoes nucleophilic...
2.8K
00:51Base-Promoted α-Halogenation of Aldehydes and Ketones
4.1K
α-Halogenation of aldehydes and ketones is a reaction involving the substitution of α hydrogens with halogens in the presence of a base. The reaction begins with the abstraction of α hydrogen by the base to produce a nucleophilic enolate ion. This intermediate undergoes a subsequent nucleophilic substitution with the halogen to produce a monohalogenated carbonyl compound. If the starting substrate has more than one α hydrogen, it is difficult to stop the reaction...
4.1K
01:13Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
7.3K
Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.
7.3K
01:21Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
4.7K
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
4.7K
03:01Halogens
23.1K
Group 17 elements, known as halogens, are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine a solid. Astatine is a highly unstable radioactive element, so currently, most of its properties are unknown due to its short half-life. Tennessine is a synthetic element also predicted to be in this group.
23.1K
02:46Halogenation of Alkenes
18.3K
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
18.3K