Fig 1.

pgl genes and glycosylation pathway in Neisseria. (A) Polymorphisms at the pgl locus of Neisseria strains. The ancestral pgl locus consists of pglF, orf2, pglH, pglB-pglB2, pglC, and pglD, while other strains lost two genes, orf2 and pglH (see Table S1 in the supplemental material). The first 40 bp of orf2 and the last 100 bp of pglH remain in the deleted pglFBCD locus (short ORF between pglF and pglB/B2). The function of orf2 is not known at the present. Both ancestral and deleted pgl loci are found in combination with both pglB and pglB2 alleles. (B) Additional pgl genes, such as pglA, pglE, pglI, and pglO, are located elsewhere in the genome. Phase-variable pgl genes are indicated with a black arrow above the genes. (C) Current model of the broad-spectrum O-linked glycosylation pathway in Neisseria. OM, outer membrane; IM, inner membrane.