Amino acid sequences of several Bacillus subtilis proteins modified by apparent guanylylation

Bacillus subtilis cell extracts, prepared at different times during growth, contained several proteins that were apparently guanylylated in vitro with [alpha-32P]-GTP. Four of the proteins were partially purified and the N-terminal amino acid sequences (13 to 20 residues) were determined. One sequence had 84% identity to Bacillus stearothermophilus triosephosphate isomerase, two were 100% identical to the predicted sequences of the B. subtilis ptsI and ptsH genes while no identity was found for the fourth sequence. This apparent guanylylation occurred with proteins involved in glucose metabolism, although the significance is unknown.