Cloning and DNA sequence of the omc gene encoding the outer membrane protein-macromolecular complex from Neisseria gonorrhoeae

Abstract

The omc gene, encoding the outer membrane protein-macromolecular complex (OMP-MC), was cloned in two pieces from Neisseria gonorrhoeae 2686. The 5' fragment of the omc gene included a promoter sequence, as indicated by its unregulated expression in Escherichia coli. Attempts to reconstruct an intact omc gene were unsuccessful, suggesting that expression of the complete OMP-MC protein was toxic to E. coli. Complete sequence determination revealed a coding sequence of 2,133 nucleotides; the deduced amino acid sequence indicated a mature protein of 687 amino acids with an NH2-terminal signal peptide of 24 amino acids. Analysis of the deduced amino acid sequence revealed that the NH2-terminal half of OMP-MC is generally hydrophilic, while the COOH-terminal portion contains alternating hydrophobic and hydrophilic regions. Serological analyses demonstrated that the NH2-terminal portion of OMP-MC is exposed on the gonococcal surface and the COOH-terminal portion is membrane associated.

Molecular analysis of a locus for the biosynthesis and phase‐variable expression of the lacto‐N‐neotetraose terminal lipopolysaccharide structure in Neisseria meningitidis

“…Database searches revealed homology with this 72bp sequence, or with subsets of the sequence, in many sequences derived from Nm and Ng. These include, in order of homology, the porA gene of Nm (McGuinness et aL, 1990), ISl106 of Nm (Knight et aL, 1992), the omc gene of Ng (Tsai et al, 1989), carA of Ng (GenBank accession number Ul1295), the tbpl and tbp2 region of Nm (Legrain et aL, 1993), the IgtA-E locus of Ng (Gotschlich, 1994), pilS1 of Ng (Haas and Meyer, 1986), and the gene for protein II of Ng (Connell et al, 1988). In all of these cases the repeat sequence is found in the intergenic regions of these sequence entries.…”

The product of the pilQ gene is essential for the biogenesis of type IV pili in Neisseria gonorrhoeae

“…These alterations, which arise, in part, from use of an altered reading frame, have surprisingly negligible effects on the predicted structural qualities of PilQ except for reducing the number of cysteine moieties from 10 to 7. The corresponding region of strain 2686 PilQ was noted for its overall basic quality, hydrophilicity and potential for exposure on the surface of the molecule (Tsai et aL, 1989), and these qualities are retained in the MS11 molecule. The amino acid-repeat segments of PilQ (encoded by either the MS11 or 2686 alleles) share little similarity to P. aeruginosa PilQ or the other homologues, nor are analogous repeat elements readily apparent in corresponding regions of the homologues.…”

“…Fragments of the piIQ gene (previously designated omc) have been cloned from Gc strain 2686, but attempts at cloning the complete gene intact were unsuccessful (Tsai et aL, 1989). Primers based on the 2686 pilQ gene sequence were used to generate a 1 kb fragment carrying the 3' end of the gene by polymerase chain reaction (PCR) Fig.…”

“…Alignment of the pilO nucleotide sequence segments from N. gonorrhoeae strains MS11 and 2686 (Tsai et al, 1989) which utilize alternative reading frames. Nucleotide position numbers and repetitive elements (denoted by dashed arrows) are indicated above the DNA sequence.…”

“…Omc was originally characterized as an abundant gonococcal outer membrane protein with a propensity to form homo-multimers of 10-12 monomers that could be dissociated only after reduction and alkylation (Newhall etaL, 1980). Interest in Omc as a gonococcal vaccine component was fostered by the observations that it appeared to account for 10% of the outer membrane protein mass (Newhall et aL, 1980), that it was conserved in strains of diverse origin, and that it was suceptible to iodination (Hansen and Wilde, 1984) and proteolysis (Tsai et aL, 1989) in whole cells. The omc gene was subsequently cloned and sequenced but the function of Omc has yet to be determined (Tsai et aL, 1989).…”