The ratio between the two TssM1 variants is critical for CTS1 T6SS function.

<p>Hcp release assays. <i>C. rodentium</i> Δ<i>tssM1</i> cells expressing WT <i>tssM1</i> (WT; producing both forms of TssM1: TssM1-FL and TssM1[1–807]) or TssM1 variants bearing mutations in the poly-A tract (AAG; producing only the TssM1[1–807] variant) or mutations in the poly-A tract and a deletion of the last nucleotide (AAG<i>Δ</i>A; producing only the TssM1-FL variant) from the pASK-IBA37+ vector (A) or producing the indicated variants from the pBAD18 and pASK-IBA37+ vectors (B). Extracellular proteins were isolated by separating whole cells (C) and the supernatant fraction (S) from cultures induced with arabinose and anhydrotetracyclin. TssM1 variants were immunodetected using the anti-FLAG monoclonal antibody (upper panels). The relative intensities of the short and long TssM1 variants are indicated (as %). Total proteins were visualized by Coomassie blue staining (lower panels). Molecular mass markers are indicated on the left.