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Table 1 Non-classical secretory proteins in bacteria. The table lists proteins known to be localised extracellularly in Gram-positive bacteria. Many of the proteins are found localised to the cell surface, where as others are found in the surrounding media. Only one study distinguish between cell surface and extracellular localisation of the proteins [21]. ClyA is the only protein from Gram-negative bacteria reported to be non-classically secreted. Proteins listed above the horizontal line have known extracellular functions (see text for details). Abbreviations: Ex – Extracellular, Cs – Cell surface, BS – B. subtilis, MT – M. tuberculosis, LM – L. monocytogenes, EC – E. coli. aCytoplasmic abundance of proteins (% of total protein in the cell) in B. subtilis ('-' no data available) [26].

From: Non-classical protein secretion in bacteria

%a Protein Score Function or similarity Species Location Reference
- FliD 0.845 Flagellar hook-associated protein 2 BS Ex [25]
- EsxB 0.813 CFP-10 MT Ex [13]
- FlgK 0.795 Flagellar hook-associated protein 1 BS Ex [25]
- XkdK 0.733 PBSX prophage gene BS Ex [25]
- XlyA 0.684 Amidase (PBSX prophage lysin) BS Ex, Cs [25,54]
- CwlC 0.634 N-Acetylmuramoyl-L-alanine amidase BS Ex, Cs [25]
- EsxA 0.557 ESAT-6, 6 kDa early secretory antigenic target MT Ex [17]
- XepA 0.545 PBSX prophage lytic exoenzyme BS Ex [25]
- XkdM 0.544 PBSX prophage gene BS Ex [25]
- GlnA 0.539 Glutamine synthetase 1 MT Ex [11,12]
- ClyA 0.225 Cytotoxic protein EC Ex [23,24]
1.27 Hag 0.218 Flagellin protein BS Cs [9,25]
1.07 SodA 0.209 Superoxide dismutase [Fe] M. tuberculosis BS, MT, LM Ex [6,9,18,28]
- XkdG 0.090 PBSX prophage gene BS Ex [9]
- ManA 0.832 Phosphomannose isomerase LM Cs [21]
- KatA 0.759 Vegetative catalase 1 BS Ex [9,25,29]
- SodA 0.701 Superoxide dismutase BS Ex [9,28]
- YceD 0.551 Similar to tellurium resistance protein BS Ex [25]
- DnaK 0.375 Heat shock protein LM Cs [6,21]
- PdhC 0.152 Pyruvate dehydrogenase (E2 subunit) LM Ex, Cs [6,21]
0.71 PdhA 0.126 Pyruvate dehydrogenase (El α subunit) BS Ex [28]
1.20 CitH 0.118 Malate dehydrogenase BS Ex [25,28]
1.20 Gap 0.118 Glyceraldehyde-3-phosphate dehydrogenase BS, LM Ex, Cs [6,9]
1.23 Eno 0.108 Enolase BS, LM Cs [6,21,25,28]
- RpoB 0.100 RNA polymerase β subunit LM Ex, Cs [21]
- RocF 0.082 Arginase BS Ex [25,28]
5.17 EF-Tu 0.075 Elongation factor Tu LM Cs [6,21]
- RS9 0.073 Ribosomal protein S9 LM Cs [21]
- RocA 0.070 Pyrroline-5 carboxylate dehydrogenase BS Ex, Cs [25]
1.91 Ef-G 0.070 Elongation factor G BS, LM Ex, Cs [6,25,28]
- RpoC 0.059 RNA polymerase β' subunit LM Ex, Cs [21]
0.76 PdhD 0.052 Pyruvate dehydrogenase (E3 subunit) BS, LM Ex [6,25,28]
- RL19 0.050 Ribosomal protein L19 LM Cs [21]
0.57 PdhB 0.047 Pyruvate dehydrogenase (El β subunit) BS Ex [25,28]
1.30 GroEL 0.035 Class I heat shock protein (chaperonin) BS Ex, Cs [21,28]