Table 1.
Identified E. coli proteins harboring hypochlorite-mediated thiol modifications
| Peptide | Protein | ICAT-modified cysteine | % oxidized before stress | % oxidized after NaOCl | Fold change | NaOCl sensitivity of mutant* | Remarks |
|---|---|---|---|---|---|---|---|
| AcnB (397–407) | Aconitase B | C404 | 37.1 | 68.0 | 1.8 | ++++ | Oxidation sensitive (29) |
| AhpC (154–169) | Thiol peroxidase | C166 | 38.0 | 63.2 | 1.7 | (+) | Cys166 forms disulfide bond in catalytic cycle (21) |
| AlaS (398–414) | Alanyl-tRNA synthetase | C413 | 16.9 | 38.6 | 2.3 | - | |
| GapA (133–160)† | Glyceraldehyde-3-P- dehydrogenase | C150/ C154 | 55.6 | 92.7 | 1.7 | NA | C150 redox-sensitive, active site residue (23) |
| GlcB (488–499) | Malate synthase | C496 | 26.9 | 54.2 | 2.0 | - | |
| GlyA (64–81)† | Serine | C66 | 22.7 | 44.7 | 2.0 | - | Diamide sensitive protein in B. subtilis (11) |
| GlyA (64–83)† | Hydroxymethyltransferase | 22.7 | 49.5 | 2.2 | |||
| GrxC (51–75) | Glutaredoxin C | C66 | 29.4 | 63.7 | 2.2 | - | C12 in active site (33) |
| GuaA (254–266) | GMP synthetase | C257 | 30.1 | 57.2 | 1.9 | ++ | C86 in active site (34) |
| HflB (243–258) | Heat shock protease | C246 | 22.9 | 48.3 | 2.1 | NA | |
| InfC (41–66) | Initiation factor 3 | C65 | 30.3 | 59.7 | 2.0 | NA | C65 single cysteine |
| Mdh (241–262)† | Malate dehydrogenase | C251 | 21.5 | 47.6 | 2.2 | ++ | |
| Ndk (128–141) | Diphosphate kinase | C139 | 31.9 | 54.7 | 1.7 | ++ | C139 single cysteine |
| PepA (15–26) | Amino peptidase | C17 | 32.5 | 61.2 | 1.9 | - | |
| Pgk (245–258) | Phosphoglycerate kinase | C249 | 25.8 | 49.6 | 1.9 | NA | Redox sensitive (31) |
| ProQ (81–100)† | Regulator of ProP | C88 | 27.8 | 57.1 | 2.1 | + | |
| RplN (79–98)† | Ribosomal protein L14 | C84 | 32.0 | 66.8 | 2.1 | NA | |
| RpsQ (44–62) | Ribosomal protein S17 | C53 | 32.4 | 62.6 | 1.9 | NA | |
| ThrB (286–299) | Homoserine kinase | C298C270 | 36.5 | 59.7 | 1.6 | (+) | |
| ThrB (247–278) | 35.4 | 63.3 | 1.8 | ||||
| Tpx (94–110)† | Thiol Peroxidase | C95 | 34.1 | 56.7 | 1.7 | - | C61 in active site (22);H2O2 sensitive in B. subtilis (11) |
| Tpx (49–66)† | C61 | 35.2 | 64.0 | 1.8 | |||
| Tpx (48–66)† | C61 | 34.3 | 63.7 | 1.9 | |||
| TufA (254–263) | Elongation Factor TU | C256 | 35.3 | 61.1 | 1.7 | +++ | NO sensitive in E. coli (32) |
| YafJ (1–25)† | Putative amidotransferase | C2/C16 | 24.9 | 55.7 | 2.2 | - | C2 invariant |
| Yggx (4–12)† | Antioxidant Protein | C7 | 23.6 | 52.5 | 2.2 | +++ | C7 single and invariant (28) |
| YhiF (80–91)‡ | Transcriptional regulator | C80 | 33.2 | 61.5 | 1.8 | ++++ |
*NA, not available (27), essential E. coli gene under our growth conditions. For sensitivity, refer SI Fig. 7 in SI Appendix.
†Peptide also identified under H2O2 stress.
‡At this mass, we additionally identified the membrane protein ugpE.