{"doi":"10.1101/2020.01.16.909523","title":"PE5-PPE4-EspG <sub>3</sub> trimer structure from mycobacterial ESX-3 secretion system gives insight into cognate substrate recognition by ESX systems","abstract":"ABSTRACT Mycobacterium tuberculosis ( Mtb ) has evolved numerous type VII secretion (ESX) systems to secrete multiple factors important for both growth and virulence across their cell envelope. Three such systems; ESX-1, ESX-3, and ESX-5; have been shown to each secrete a unique set of substrates. A large class of these substrates secreted by these three systems are the PE and PPE families of proteins. Proper secretion of the PE-PPE proteins requires the presence of EspG, with each system encoding its own unique copy. There is no cross-talk between any of the ESX systems and how each EspG is recognizing its subset of PE-PPE proteins is currently unknown. The only current structural characterization of PE-PPE-EspG trimers is from the ESX-5 system. Here we present the crystal structure of the PE5 mt -PPE4 mt -EspG 3mm trimer, from the ESX-3 system. Our trimer reveals that EspG 3mm interacts exclusively with PPE4 mt in a similar manner to EspG 5 , shielding the hydrophobic tip of PPE4 mt from solvent. The C-terminal helical domain of EspG 3mm is dynamic, alternating between an ‘open’ and ‘closed’ form, and this movement is likely functionally relevant in the unloading of PE-PPE heterodimers at the secretion machinery. In contrast to the previously solved ESX-5 trimers, the PE-PPE heterodimer of our ESX-3 trimer is interacting with it’s chaperone at a drastically different angle, and presents different faces of the PPE protein to the chaperone. We conclude that the PPE-EspG interface from each ESX system has a unique shape complementarity that allows each EspG to discriminate amongst non-cognate PE-PPE pairs.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2020,"id":126128,"datarank":0.10397207708399181,"base_score":0.6931471805599453,"endowment":0.6931471805599453,"self_citation_contribution":0.10397207708399181,"citation_network_contribution":0.0,"self_endowment_contribution":0.10397207708399181,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9586,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":540786,"name":"Catherine T. Chaton","orcid":"0000-0002-2843-3559","position":1,"is_corresponding":false},{"id":574150,"name":"William A. Ciocca","orcid":null,"position":2,"is_corresponding":false},{"id":573534,"name":"Natalia Korotkova","orcid":"0000-0002-8696-4892","position":3,"is_corresponding":false},{"id":573535,"name":"Konstantin V. Korotkov","orcid":"0000-0002-2182-6843","position":4,"is_corresponding":false},{"id":573533,"name":"Zachary A. Williamson","orcid":"0000-0002-7070-5693","position":0,"is_corresponding":true}],"reference_count":34,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T23:15:23.509897Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}