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Secretion of atypical protein substrates by the ESAT ‐6 S ecretion S ystem of S taphylococcus aureus
Author(s) -
Anderson Mark,
Aly Khaled A.,
Chen YiHsing,
Missiakas Dominique
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12395
Subject(s) - secretion , esat 6 , biology , peptide sequence , amino acid , secretory protein , virulence , clan , gene , microbiology and biotechnology , biochemistry , genetics , bacterial protein , sociology , anthropology
Summary S taphylococcus aureus encodes the specialized ESAT ‐6 S ecretion S ystem ( ESS ). EsxA and EsxB are secreted by the ESS pathway, and share sequence features of ESAT ‐6 and CFP ‐10 of the T ype VII S ecretion S ystem ( T 7 SS ) of M ycobacterium tuberculosis . Unlike ESAT ‐6 and CFP ‐10, EsxA and EsxB do not interact. Instead, EsxB associates with a novel substrate, EsxD , and EsxA dimerizes with itself or EsxC ( EsaC ). Unlike EsxA and EsxB , EsxC and EsxD do not share obvious sequence features of WXG 100 proteins nor PE / PPE and Esp families of proteins, all of which belong to the pfam EsxAB clan of mycobacterial T 7 SS . EsxD carries the C ‐terminal motif YxxxD / E that has been proposed to target T 7 substrates for secretion in mycobacteria. Here, we find that deletion, but not amino acid substitutions, in this motif prevent secretion of EsxA and EsxC but not EsxB or EsxD . This is unlike the genetic inactivation of esxA , esxB , esxC or esxD that leads to loss of secretion of all four substrates. Thus, substrate secretion can be uncoupled by deleting the last six amino acids of EsxD . The physical association of EsxC and EsxD with canonical WXG 100 proteins suggests that these proteins belong to the EsxAB clan.