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New insights into the domain of unknown function (DUF) of EccC5, the pivotal ATPase providing the secretion driving force to the ESX-5 secretion system

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Title: New insights into the domain of unknown function (DUF) of EccC5, the pivotal ATPase providing the secretion driving force to the ESX-5 secretion system
Authors: Fernando Ceballos-Zúñiga, Margarita Menéndez, Inmaculada Pérez-Dorado
Contributors: Comunidad de Madrid, Instituto de Salud Carlos III, Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
Source: Acta Crystallogr D Struct Biol
Digital.CSIC. Repositorio Institucional del CSIC
Consejo Superior de Investigaciones Científicas (CSIC)
Publisher Information: International Union of Crystallography (IUCr), 2024.
Publication Year: 2024
Subject Terms: Adenosine Triphosphatases, Models, Molecular, DUF domain of EccC5, ESX systems, Crystallography, Virulence Factors, Mycobacteria, Mycobacterium tuberculosis, Crystallography, X-Ray, ATPase activity, Research Papers, 3. Good health, Secretion systems, Bacterial Proteins, Protein Domains, T7SS, Type VII Secretion Systems, Humans
Description: Type VII secretion (T7S) systems, also referred to as ESAT-6 secretion (ESX) systems, are molecular machines that have gained great attention due to their implications in cell homeostasis and in host–pathogen interactions in mycobacteria. The latter include important human pathogens such as Mycobacterium tuberculosis (Mtb), the etiological cause of human tuberculosis, which constitutes a pandemic accounting for more than one million deaths every year. The ESX-5 system is exclusively found in slow-growing pathogenic mycobacteria, where it mediates the secretion of a large family of virulence factors: the PE and PPE proteins. The secretion driving force is provided by EccC5, a multidomain ATPase that operates using four globular cytosolic domains: an N-terminal domain of unknown function (EccC5 DUF) and three FtsK/SpoIIIE ATPase domains. Recent structural and functional studies of ESX-3 and ESX-5 systems have revealed EccCDUF to be an ATPase-like fold domain with potential ATPase activity, the functionality of which is essential for secretion. Here, the crystal structure of the MtbEccC5 DUF domain is reported at 2.05 Å resolution, which reveals a nucleotide-free structure with degenerated cis-acting and trans-acting elements involved in ATP binding and hydrolysis. This crystallographic study, together with a biophysical assessment of the interaction of MtbEccC5 DUF with ATP/Mg2+, supports the absence of ATPase activity proposed for this domain. It is shown that this degeneration is also present in DUF domains from other ESX and ESX-like systems, which are likely to exhibit poor or null ATPase activity. Moreover, based on an in silico model of the N-terminal region of MtbEccC5 DUF, it is hypothesized that MtbEccC5 DUF is a degenerated ATPase domain that may have retained the ability to hexamerize. These observations draw attention to DUF domains as structural elements with potential implications in the opening and closure of the membrane pore during the secretion process via their involvement in inter-protomer interactions.
Document Type: Article
Other literature type
ISSN: 2059-7983
DOI: 10.1107/s2059798324004248
DOI: 10.1101/2024.01.26.577026
DOI: 10.13039/100012818
DOI: 10.13039/501100004587
Access URL: https://pubmed.ncbi.nlm.nih.gov/38805245
http://hdl.handle.net/10261/371090
https://api.elsevier.com/content/abstract/scopus_id/85195348429
Rights: CC BY
URL: http://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Accession Number: edsair.doi.dedup.....3c7141b8a9af4c59d89f760a80d67be3
Database: OpenAIRE
Description
Abstract:Type VII secretion (T7S) systems, also referred to as ESAT-6 secretion (ESX) systems, are molecular machines that have gained great attention due to their implications in cell homeostasis and in host–pathogen interactions in mycobacteria. The latter include important human pathogens such as Mycobacterium tuberculosis (Mtb), the etiological cause of human tuberculosis, which constitutes a pandemic accounting for more than one million deaths every year. The ESX-5 system is exclusively found in slow-growing pathogenic mycobacteria, where it mediates the secretion of a large family of virulence factors: the PE and PPE proteins. The secretion driving force is provided by EccC5, a multidomain ATPase that operates using four globular cytosolic domains: an N-terminal domain of unknown function (EccC5 DUF) and three FtsK/SpoIIIE ATPase domains. Recent structural and functional studies of ESX-3 and ESX-5 systems have revealed EccCDUF to be an ATPase-like fold domain with potential ATPase activity, the functionality of which is essential for secretion. Here, the crystal structure of the MtbEccC5 DUF domain is reported at 2.05 Å resolution, which reveals a nucleotide-free structure with degenerated cis-acting and trans-acting elements involved in ATP binding and hydrolysis. This crystallographic study, together with a biophysical assessment of the interaction of MtbEccC5 DUF with ATP/Mg2+, supports the absence of ATPase activity proposed for this domain. It is shown that this degeneration is also present in DUF domains from other ESX and ESX-like systems, which are likely to exhibit poor or null ATPase activity. Moreover, based on an in silico model of the N-terminal region of MtbEccC5 DUF, it is hypothesized that MtbEccC5 DUF is a degenerated ATPase domain that may have retained the ability to hexamerize. These observations draw attention to DUF domains as structural elements with potential implications in the opening and closure of the membrane pore during the secretion process via their involvement in inter-protomer interactions.
ISSN:20597983
DOI:10.1107/s2059798324004248