Use of xylE fusions to demonstrate that lsi-1, a Neisseria gonorrhoeae lipooligosaccharide biosynthetic gene, and lsi-3 are not transcriptionally linked

The Neisseria gonorr*oeae lipooligosaccharide biosynthetic gene _hi-i is preceded by a 281-bp non-protein-encoding sequence, li-3, that contains two pairs of inverted repeats. Gonococcal chromosomal lsi-xylE gpne fusions were generated to measure the effect of the secondkry structure on transcriptional attenuation. The data obtained indicate that lsi-3 and lsi- are not transcriptionally linked and therefore that si-3 is not involved in the regulation of hi-i. Lipooligosaccharide (LOS) is an important virulence deter-minant of Neisseria gonorrhoeae (5, 7, 19, 21, 25, 28). An individual strain of N. gonorrhoeae may simultaneously express a variety of different-size LOS components (6, 11, 19) that can undergo antigenic variation at high frequencies (20). In vitro growth conditions have been shown to influence the expression of LOS (1, 13, 14), suggesting that the gonococcus has the potential to alter its LOS during in vivo growth. The mecha-nism allowing for this structural diversity and antigenic varia-tion is not known