Polypeptides encoded by cryptic plasmids from Neisseria gonorrhoeae

Evaluation of an rRNA-derived oligonucleotide probe for culture confirmation of Neisseria gonorrhoeae

The reliability of an rRNA-derived oligonucleotide probe for Neisseria gonorrhoeae was tested with 187 N. gonorrhoeae isolates, 81 Neisseria meningitidis isolates, and several strains of other bacterial species. The probe proved to be 100% specific and 100% sensitive. N. gonorrhoeae cells could also be reliably identified in contaminated cultures with the oligonucleotide probe. The 2.6-megadalton cryptic plasmid used as a probe for N. gonorrhoeae was shown to be less sensitive, detecting 179 of 181 N. gonorrhoeae isolates.

Subcellular localization of proteins encoded by the phenotypically cryptic plasmid of Neisseria gonorrhoeae: biological evidence for outer membrane association of the cppB gene product

Almost all clinical isolates of Neisseria gonorrhoeae harbour a plasmid of 4.2 kb with no known function. A genetic model based on the DNA sequence of the plasmid, with ten open reading frames, has been proposed by Korch et al., (1985). To address the question of the function of the encoded proteins, some of which are expressed when the plasmid is harboured by Escherichia coli, the subcellular locations of such proteins were investigated in minicells of Escherichia coli DS410. The protein CppB, earlier proposed to be a membrane-spanning polypeptide, was found associated with the outer membrane. Up to five other cryptic plasmid proteins were found to be localized in the periplasm.

A novel insertion sequence in the cryptic plasmid of Neisseria gonorrhoeae may alter the B protein at the translational level

A variant of the cryptic plasmid of Neisseria gonorrhoeae, 4.4 kb in size, was isolated and characterized at the molecular level. This variant harbored a 156-bp insertion which was located between coordinates 3134 and 3135 within the putative cppB gene using the 4.2-kb cryptic plasmid, pJD1, as a reference. The insertion contained a novel EcoRI site and several elements of symmetry (both direct and inverted repeats). Stop codons present in the insertion interrupted the coding capacity of the cppB gene. Although the insertion was within one of two previously characterized 44-bp repeats purportedly involved in site-specific recombination, it was distinct from a 54-bp segment deleted in some cryptic plasmids. The presence of the insertion suggests a mechanism of modulating the expression of the cppB gene at the translational level through DNA rearrangement.