Table 3 Strains and plasmids used in this study

Strains

 E. coli DH5α

F⁻ Ф80dlacZΔ (lacZYA-argF) U169 recA1 endA1 hsdR 17 (r ⁻ _k m ⁺ _k ) supE44 λ ⁻ thi-1 gyrA relA1

Lab. strain

 B. subtilis 168

trpC2

Lab. strain

 B. subtilis WB800

nprE aprE epr bpr mpr::ble nprB::bsr vpr wprA::hyg

[28]

Plasmids

 pMA5ΔMCS

An intermediate plasmid excised from the original cloning site of pMA5

[17]

 p-Nsp-his

Encodes the unstructured protein Nsp

[17]

 p-ssPhoD-Nsp-his

Encodes Nsp fused with signal peptide of PhoD

[17]

 p-ssNprE-BgaB-his

Encodes BgaB fused with the signal peptide of NprE

This study

 p-NCP-Nsp-his^a

Encodes four non-classically secreted protein-Nsp fusions

This study

 p-NCP-PhoA-his

Encodes four non-classically secreted protein-PhoA fusions

This study

 p-YvgN50-Nsp-his

Encodes the first 50 amino acids of YvgN fused with Nsp

This study

 p-PhoA-his

Encodes intact Escherichia coli PhoA

This study

 p-NCP-BgaB-his

Encodes four non-classically secreted protein-BgaB fusions

This study