IDENTIFICATION OF AN EF-TU PROTEIN THAT IS PERIPLASM-ASSOCIATED AND PROCESSED IN NEISSERIA-GONORRHOEAE

A 44 kDa protein is a dominant component of periplasmic extracts of Ne isseria gonorrhoeae. Peptide sequence generated from a cyanogen-bromid e-cleaved fragment of this protein indicated sequence homology with el ongation factor-Tu (EF-Tu). Polyclonal antiserum was made against the 44 kDa protein purified from periplasm extracts of N. gonorrhoeae. The preabsorbed antiserum was immunoblotted against whole-cell lysates on two-dimensional gels. A 44 kDa protein and a smaller 37 kDa protein w ere recognized by this antiserum. A N. gonorrhoeae lambda phage DNA li brary was screened and a clone expressing a 44 kDa protein was identif ied. The DNA insert in this clone contained several genes homologous t o genes contained in the str operon of Escherichia coli. One ORF produ ct with a calculated molecular mass of 43 kDa was highly homologous to the EF-TuA of E. coli. A synthetic peptide antiserum specific for a p ortion of the C terminus of EF-Tu confirmed that the 37 kDa protein in whole-cell lysates of N. gonorrhoeae was a processed form of EF-Tu. D eletion of the tufA gene homologue in N. gonorrhoeae was attempted but was unsuccessful.