Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway

Triuret (carbonyldiurea) is an impurity found in industrial urea fertilizer (<0.1% w/w) that is applied, worldwide, around 300 million pounds each year on agricultural lands. In addition to anthropogenic sources, endogenous triuret has been identified in amoeba and human urine, the latter being d...

Descripción completa

Detalles Bibliográficos
Autores principales: Tassoulas, Lambros J., Elias, Mikael H., Wackett, Lawrence P.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948467/
https://www.ncbi.nlm.nih.gov/pubmed/33172891
http://dx.doi.org/10.1074/jbc.RA120.015631
_version_ 1783663414974873600
author Tassoulas, Lambros J.
Elias, Mikael H.
Wackett, Lawrence P.
author_facet Tassoulas, Lambros J.
Elias, Mikael H.
Wackett, Lawrence P.
author_sort Tassoulas, Lambros J.
collection PubMed
description Triuret (carbonyldiurea) is an impurity found in industrial urea fertilizer (<0.1% w/w) that is applied, worldwide, around 300 million pounds each year on agricultural lands. In addition to anthropogenic sources, endogenous triuret has been identified in amoeba and human urine, the latter being diagnostic for hypokalemia. The present study is the first to describe the metabolic breakdown of triuret, which funnels into biuret metabolism. We identified the gene responsible for triuret decomposition (trtA) in bacterial genomes, clustered with biuH, which encodes biuret hydrolase and has close protein sequence homology. TrtA is a member of the isochorismatase-like hydrolase (IHL) protein family, similarly to BiuH, and has a catalytic efficiency (k(cat/)K(M)) of 6 x 10(5) M(−1)s(−1), a K(M) for triuret of 20 μM, and exquisite substrate specificity. Indeed, TrtA has four orders of magnitude less activity with biuret. Crystal structures of TrtA in apo and holo form were solved and compared with the BiuH structure. The high substrate selectivity was found to be conveyed by second shell residues around each active site. Mutagenesis of residues conserved in TrtA to the alternate consensus found in BiuHs revealed residues critical to triuret hydrolase activity but no single mutant evolved more biuret activity, and likely a combination of mutations is required to interconvert between TrtA, BiuH functions. TrtA-mediated triuret metabolism is relatively rare in recorded genomes (1–2%), but is largely found in plant-associated, nodulating, and endophytic bacteria. This study suggests functions for triuret hydrolase in certain eukaryotic intermediary processes and prokaryotic intermediary or biodegradative metabolism
format Online
Article
Text
id pubmed-7948467
institution National Center for Biotechnology Information
language English
publishDate 2020
publisher American Society for Biochemistry and Molecular Biology
record_format MEDLINE/PubMed
spelling pubmed-79484672021-03-19 Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway Tassoulas, Lambros J. Elias, Mikael H. Wackett, Lawrence P. J Biol Chem Research Article Triuret (carbonyldiurea) is an impurity found in industrial urea fertilizer (<0.1% w/w) that is applied, worldwide, around 300 million pounds each year on agricultural lands. In addition to anthropogenic sources, endogenous triuret has been identified in amoeba and human urine, the latter being diagnostic for hypokalemia. The present study is the first to describe the metabolic breakdown of triuret, which funnels into biuret metabolism. We identified the gene responsible for triuret decomposition (trtA) in bacterial genomes, clustered with biuH, which encodes biuret hydrolase and has close protein sequence homology. TrtA is a member of the isochorismatase-like hydrolase (IHL) protein family, similarly to BiuH, and has a catalytic efficiency (k(cat/)K(M)) of 6 x 10(5) M(−1)s(−1), a K(M) for triuret of 20 μM, and exquisite substrate specificity. Indeed, TrtA has four orders of magnitude less activity with biuret. Crystal structures of TrtA in apo and holo form were solved and compared with the BiuH structure. The high substrate selectivity was found to be conveyed by second shell residues around each active site. Mutagenesis of residues conserved in TrtA to the alternate consensus found in BiuHs revealed residues critical to triuret hydrolase activity but no single mutant evolved more biuret activity, and likely a combination of mutations is required to interconvert between TrtA, BiuH functions. TrtA-mediated triuret metabolism is relatively rare in recorded genomes (1–2%), but is largely found in plant-associated, nodulating, and endophytic bacteria. This study suggests functions for triuret hydrolase in certain eukaryotic intermediary processes and prokaryotic intermediary or biodegradative metabolism American Society for Biochemistry and Molecular Biology 2020-12-01 /pmc/articles/PMC7948467/ /pubmed/33172891 http://dx.doi.org/10.1074/jbc.RA120.015631 Text en © 2020 The Authors https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Research Article
Tassoulas, Lambros J.
Elias, Mikael H.
Wackett, Lawrence P.
Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway
title Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway
title_full Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway
title_fullStr Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway
title_full_unstemmed Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway
title_short Discovery of an ultraspecific triuret hydrolase (TrtA) establishes the triuret biodegradation pathway
title_sort discovery of an ultraspecific triuret hydrolase (trta) establishes the triuret biodegradation pathway
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948467/
https://www.ncbi.nlm.nih.gov/pubmed/33172891
http://dx.doi.org/10.1074/jbc.RA120.015631
work_keys_str_mv AT tassoulaslambrosj discoveryofanultraspecifictriurethydrolasetrtaestablishesthetriuretbiodegradationpathway
AT eliasmikaelh discoveryofanultraspecifictriurethydrolasetrtaestablishesthetriuretbiodegradationpathway
AT wackettlawrencep discoveryofanultraspecifictriurethydrolasetrtaestablishesthetriuretbiodegradationpathway