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Functional analysis of the EsaB component of the Staphylococcus aureus type VII secretion system

Lookup NU author(s): Dr Guillermina Casabona, Dr Grant Buchanan, Professor Tracy Palmer FRS FRSE FMedSciORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2017 The Authors. Type VII secretion systems (T7SS) are found in many bacteria and secrete proteins involved in virulence and bacterial competition. In Staphylococcus aureus the small ubiquitin-like EsaB protein has been previously implicated as having a regulatory role in the production of the EsxC substrate. Here we show that in the S. aureus RN6390 strain, EsaB does not genetically regulate production of any T7 substrates or components, but is indispensable for secretion activity. Consistent with EsaB being an essential component of the T7SS, loss of either EsaB or EssC are associated with upregulation of a common set of iron acquisition genes. However, a further subset of genes were dysregulated only in the absence of EsaB. Quantitative western blotting indicates that EsaB is present at very low levels in cells. Substitution of a highly conserved threonine for alanine or arginine resulted in a loss of EsaB activity and destabilisation of the protein. Taken together our findings show that EsaB is essential for T7SS activity in RN6390.

Publication metadata

Author(s): Casabona MG, Buchanan G, Zoltner M, Harkins CP, Holden MTG, Palmer T

Publication type: Article

Publication status: Published

Journal: Microbiology

Year: 2017

Volume: 163

Issue: 12

Pages: 1851-1863

Print publication date: 01/12/2017

Online publication date: 22/11/2017

Acceptance date: 14/11/2017

Date deposited: 14/02/2019

ISSN (print): 1350-0872

ISSN (electronic): 1465-2080

Publisher: Microbiology Society


DOI: 10.1099/mic.0.000580


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