Septal secretion of protein A in Staphylococcus aureus requires SecA and lipoteichoic acid synthesis

• Main Authors: Wenqi Yu, Dominique Missiakas, Olaf Schneewind
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2018-05-01
• Series: eLife
• Subjects: Staphylococcus aureus; staphylococcal protein A; YSIRK-GXXS motif; lipoteichoic acid; LtaS; cross-wall
• Online Access: https://elifesciences.org/articles/34092

Surface proteins of Staphylococcus aureus are secreted across septal membranes for assembly into the bacterial cross-wall. This localized secretion requires the YSIRK/GXXS motif signal peptide, however the mechanisms supporting precursor trafficking are not known. We show here that the signal peptide of staphylococcal protein A (SpA) is cleaved at the YSIRK/GXXS motif. A SpA signal peptide mutant defective for YSIRK/GXXS cleavage is also impaired for septal secretion and co-purifies with SecA, SecDF and LtaS. SecA depletion blocks precursor targeting to septal membranes, whereas deletion of secDF diminishes SpA secretion into the cross-wall. Depletion of LtaS blocks lipoteichoic acid synthesis and abolishes SpA precursor trafficking to septal membranes. We propose a model whereby SecA directs SpA precursors to lipoteichoic acid-rich septal membranes for YSIRK/GXXS motif cleavage and secretion into the cross-wall.