Table 1.
Acetylation sites of CheY in vivo revealed from MS/MS analyses
| Peptide Sequence | Acetylation site on CheYa |
MH+ [Da]b | Xcorrc |
|---|---|---|---|
| Wild-type level of CheY (no IPTG) | |||
| ATLEEKLNacKIFEacKLGMGLCG | K122; K126 | 2351.21573 | 2.2 |
| Wild-type level of CheY (no IPTG) + acetate | |||
| HHTDPALRAADacKELacK | K4; K7 | 1785.91252 | 2.36 |
| DALNKLQAGGYGFVISDWNMPNMDGLELLacKTIR | K70 | 3724.82656 | 3.16 |
| AacKKENIIAAAQAG | K91 | 1328.71623 | 2.06 |
| LMVTAEAKacKENIIAAAQAGASG | K92 | 2202.14408 | 2.11 |
| LNacKIFEK | K122 | 933.53984 | 2.75 |
| Elevated levels of CheY (IPTG) | |||
| VVacKPFTAATLEEKLNK | K109 | 1830.02666 | 3.21 |
| LEEacKLNKI | K119 | 1028.59380 | 1.91 |
| TAATLEEacKLNKIFEacKL | K119; K126 | 1933.04265 | 1.86 |
| Elevated levels of CheY (IPTG) + acetate | |||
| ALPVLMVTAEAacKKENIIAAAQ | K91 | 2240.21514 | 2.17 |
| VVacKPFTAATLEEKLNK | K109 | 1830.02666 | 3.07 |
| LEEacKLNKI | K119 | 1028.59380 | 1.98 |
| TAATLEEacKLNKIFEacKL | K119; K126 | 1933.0265 | 1.92 |
a
According to protein accession P0AE67. The sites were determined according to acetylated peptides obtained by proteolytic digestion with trypsin and chymotrypsin.
b
MH+ is the mass of the protonated form of the peptide.
c
Xcorr is a cross-correlation score function calculated to assess the quality of the match between a tandem mass spectrum and amino acid sequence information in a database (Eng et al., 1994). The peptides were identified using the Sequest search engine.