A novel efficient producer of human ω-amidase (Nit2) in Escherichia coli

Nit2/ω-amidase catalyzes the hydrolysis of α-ketoglutaramate (KGM, the α-keto acid analogue of glutamine) to α-ketoglutarate and ammonia. The enzyme also catalyzes the amide hydrolysis of monoamides of 4- and 5-C-dicarboxylates, including α-ketosuccinamate (KSM, the α-keto acid analogue of asparagin...

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Bibliographic Details
Published in:Analytical biochemistry 2021-11, Vol.632, p.114332-114332, Article 114332
Main Authors: Epova, Ekaterina Yu, Shevelev, Alexei B., Shurubor, Yevgeniya I., Cooper, Arthur J.L., Biryukova, Yulia K., Bogdanova, Elena S., Tyno, Yaroslav Ya, Lebedeva, Anna A., Krasnikov, Boris F.
Format: Article
Language:English
Subjects:
Aminohydrolases - biosynthesis
Aminohydrolases - chemistry
Aminohydrolases - genetics
Escherichia coli
Escherichia coli - metabolism
Expression
Glutamine transaminases
Human Nit2
Humans
Purification
ω-Amidase
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Summary:Nit2/ω-amidase catalyzes the hydrolysis of α-ketoglutaramate (KGM, the α-keto acid analogue of glutamine) to α-ketoglutarate and ammonia. The enzyme also catalyzes the amide hydrolysis of monoamides of 4- and 5-C-dicarboxylates, including α-ketosuccinamate (KSM, the α-keto acid analogue of asparagine) and succinamate (SM). Here we describe an inexpensive procedure for high-yield expression of human Nit2 (hNit2) in Escherichia coli and purification of the expressed protein. This work includes: 1) the design of a genetic construct (pQE-Nit22) obtained from the previously described construct (pQE-Nit2) by replacing rare codons within an 81 bp-long DNA fragment “preferred” by E. coli near the translation initiation site; 2) methods for producing and maintaining the pQE-Nit22 construct; 3) purification of recombinant hNit2; and 4) activity measurements of the purified enzyme with KGM and SM. Important features of the hNit2 gene within the pQE-Nit22 construct are: 1) optimized codon composition, 2) the presence of an N-terminus His6 tag immediately after the initiating codon ATG (Met) that permits efficient purification of the end-product on a Ni-NTA-agarose column. We anticipate that the availability of high yield hNit2/ω-amidase will be helpful in elucidating the normal and pathological roles of this enzyme and in the design of specific inhibitors. Functional map of pQE-Nit22 plasmid constuct encoding human Nit2/ω-amidase containing an N-terminal His6 tag. [Display omitted] •Glutaminase II pathway: Gln transaminase (Gln + α-keto acid → α-ketoglutaramate (KGM) + l-amino acid) plus ω-amidase (KGM + H2O → KG + NH4+) (net: Gln + α-keto acid + H2O → KG + l-amino acid + NH4+)•Many rapidly dividing cells, including cancer cells, convert Gln to anaplerotic KG as an energy source, and one such pathway for conversion of Gln to KG is the overlooked glutaminase II pathway•We previously described a plasmid (pQE-Nit2) for the production of ω-amidase (annotated as Nit2 in the human genome) in E. coli that utilizes codons for Arg and Ile seldom used in this bacterium•Here we describe a new plasmid (pQE-Nit22) wherein codons for Arg/Ile that are rare in E. coli in the hNit2 gene are replaced by more commonly used codons just beyond the translation initiation site•This novel construct produces high-yield, active human ω-amidase which will be useful for determining biological roles of this enzyme and the design of selective inhibitors as possible anti-cancer agents
ISSN:0003-2697
1096-0309
DOI:10.1016/j.ab.2021.114332