Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase

Abstract Contact-dependent growth inhibition (CDI) is a wide-spread mechanism of inter-bacterial competition. CDI+ bacteria deliver CdiA-CT toxins into neighboring bacteria and produce specific immunity proteins that protect against self-intoxication. The CdiA-CT toxin from uropathogenic Escherichia...

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Autores principales:	Roberto Benoni, Christina M. Beck, Fernando Garza-Sánchez, Stefano Bettati, Andrea Mozzarelli, Christopher S. Hayes, Barbara Campanini
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/732d3ba865a64bc080482b3e982d4bbc
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spelling	oai:doaj.org-article:732d3ba865a64bc080482b3e982d4bbc2021-12-02T15:05:51ZActivation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase10.1038/s41598-017-09022-62045-2322https://doaj.org/article/732d3ba865a64bc080482b3e982d4bbc2017-08-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-09022-6https://doaj.org/toc/2045-2322Abstract Contact-dependent growth inhibition (CDI) is a wide-spread mechanism of inter-bacterial competition. CDI+ bacteria deliver CdiA-CT toxins into neighboring bacteria and produce specific immunity proteins that protect against self-intoxication. The CdiA-CT toxin from uropathogenic Escherichia coli 536 is a latent tRNase that is only active when bound to the cysteine biosynthetic enzyme CysK. Remarkably, the CysK:CdiA-CT binding interaction mimics the ‘cysteine synthase’ complex of CysK:CysE. The C-terminal tails of CysE and CdiA-CT each insert into the CysK active-site cleft to anchor the respective complexes. The dissociation constant for CysK:CdiA-CT (K d ~ 11 nM) is comparable to that of the E. coli cysteine synthase complex (K d ~ 6 nM), and both complexes bind through a two-step mechanism with a slow isomerization phase after the initial encounter. However, the second-order rate constant for CysK:CdiA-CT binding is two orders of magnitude slower than that of the cysteine synthase complex, suggesting that CysE should outcompete the toxin for CysK occupancy. However, we find that CdiA-CT can effectively displace CysE from pre-formed cysteine synthase complexes, enabling toxin activation even in the presence of excess competing CysE. This adventitious binding, coupled with the very slow rate of CysK:CdiA-CT dissociation, ensures robust nuclease activity in target bacteria.Roberto BenoniChristina M. BeckFernando Garza-SánchezStefano BettatiAndrea MozzarelliChristopher S. HayesBarbara CampaniniNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-16 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Roberto Benoni Christina M. Beck Fernando Garza-Sánchez Stefano Bettati Andrea Mozzarelli Christopher S. Hayes Barbara Campanini Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase
description	Abstract Contact-dependent growth inhibition (CDI) is a wide-spread mechanism of inter-bacterial competition. CDI+ bacteria deliver CdiA-CT toxins into neighboring bacteria and produce specific immunity proteins that protect against self-intoxication. The CdiA-CT toxin from uropathogenic Escherichia coli 536 is a latent tRNase that is only active when bound to the cysteine biosynthetic enzyme CysK. Remarkably, the CysK:CdiA-CT binding interaction mimics the ‘cysteine synthase’ complex of CysK:CysE. The C-terminal tails of CysE and CdiA-CT each insert into the CysK active-site cleft to anchor the respective complexes. The dissociation constant for CysK:CdiA-CT (K d ~ 11 nM) is comparable to that of the E. coli cysteine synthase complex (K d ~ 6 nM), and both complexes bind through a two-step mechanism with a slow isomerization phase after the initial encounter. However, the second-order rate constant for CysK:CdiA-CT binding is two orders of magnitude slower than that of the cysteine synthase complex, suggesting that CysE should outcompete the toxin for CysK occupancy. However, we find that CdiA-CT can effectively displace CysE from pre-formed cysteine synthase complexes, enabling toxin activation even in the presence of excess competing CysE. This adventitious binding, coupled with the very slow rate of CysK:CdiA-CT dissociation, ensures robust nuclease activity in target bacteria.
format	article
author	Roberto Benoni Christina M. Beck Fernando Garza-Sánchez Stefano Bettati Andrea Mozzarelli Christopher S. Hayes Barbara Campanini
author_facet	Roberto Benoni Christina M. Beck Fernando Garza-Sánchez Stefano Bettati Andrea Mozzarelli Christopher S. Hayes Barbara Campanini
author_sort	Roberto Benoni
title	Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase
title_short	Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase
title_full	Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase
title_fullStr	Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase
title_full_unstemmed	Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase
title_sort	activation of an anti-bacterial toxin by the biosynthetic enzyme cysk: mechanism of binding, interaction specificity and competition with cysteine synthase
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/732d3ba865a64bc080482b3e982d4bbc
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Activation of an anti-bacterial toxin by the biosynthetic enzyme CysK: mechanism of binding, interaction specificity and competition with cysteine synthase

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