Crystals of acetylated SecB diffract to 2.3-angstrom resolution

The molecular chaperone SecB is part of the protein translocation pathway i n Escherichia coli. SecB was purified from an overproducing strain and crys tallized, resulting in crystals diffracting to 2.3-Angstrom resolution. The analysis of electrospray ionization mass spectra of dissolved crystals of SecB indicated that we have crystallized an acetylated form of SecB. Sequen ce analysis suggests that the protein is fully acetylated at its N-terminus in vivo, indicating that potential deacetylation is artificially introduce d by purification methods. The high degree of acetylation that we observed might account for the fact that the crystals obtained as described in this study diffract to higher resolution than those in previously reported trial s. (C) 1999 Academic Press.