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Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein

The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bac...

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Autores principales: Wang, Tianyu, Ding, Jinjing, Zhang, Ying, Wang, Da-Cheng, Liu, Wei
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3792639/
https://www.ncbi.nlm.nih.gov/pubmed/24100309
http://dx.doi.org/10.1107/S090744491301576X
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author Wang, Tianyu
Ding, Jinjing
Zhang, Ying
Wang, Da-Cheng
Liu, Wei
author_facet Wang, Tianyu
Ding, Jinjing
Zhang, Ying
Wang, Da-Cheng
Liu, Wei
author_sort Wang, Tianyu
collection PubMed
description The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for niches via amidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1–Tsi1 has been structurally characterized. Here, the structure of the Tse3–Tsi3 complex is reported at 1.9 Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a β-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3–Tsi3 effector–immunity pair.
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spelling pubmed-37926392013-10-08 Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein Wang, Tianyu Ding, Jinjing Zhang, Ying Wang, Da-Cheng Liu, Wei Acta Crystallogr D Biol Crystallogr Research Papers The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for niches via amidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1–Tsi1 has been structurally characterized. Here, the structure of the Tse3–Tsi3 complex is reported at 1.9 Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a β-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3–Tsi3 effector–immunity pair. International Union of Crystallography 2013-10-01 2013-09-20 /pmc/articles/PMC3792639/ /pubmed/24100309 http://dx.doi.org/10.1107/S090744491301576X Text en © Wang et al. 2013 http://creativecommons.org/licenses/by/2.0/uk/ This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
spellingShingle Research Papers
Wang, Tianyu
Ding, Jinjing
Zhang, Ying
Wang, Da-Cheng
Liu, Wei
Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
title Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
title_full Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
title_fullStr Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
title_full_unstemmed Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
title_short Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
title_sort complex structure of type vi peptidoglycan muramidase effector and a cognate immunity protein
topic Research Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3792639/
https://www.ncbi.nlm.nih.gov/pubmed/24100309
http://dx.doi.org/10.1107/S090744491301576X
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