FIG. 2.

(a) Alignment (MEGALIGN) of DNA sequence 256 bp upstream of lav homologs. Strain designations are as described for Fig. 1, except that NM-B is MC58 and NM-A is Z2491. The initiating codon (complementary strand) of holB is indicated (left arrow), and the sequence includes 19 codons at the N terminus-encoding portion of of holB. The start of lav is also indicated (right arrow). An 18-bp sequence from an hUS is underlined; this sequence has been duplicated from a paired hUS at the tmk end of the Int1 lav island. (b) Phylograms of aligned sequences from the 256-bp upstream sequence (5′ to lav), from the β-barrel region (last 385 codons, including the predicted linker region), and from rpoD (17, 36, 48). Phylogenies were derived with the ClustalV program of MEGALIGN, using a combination of the unweighted pair group method using arithmetic averages algorithm and the neighbor-joining method (39, 46). (c) H. influenzae lav is anomalously similar to its N. meningitidis homologs relative to pairwise comparisons between housekeeping genes shared by H. influenzae and N. meningitidis. Linear regression of inferred amino acid sequence identity on DNA identity of 12 housekeeping genes (open squares) in N. meningitidis serotype B and H. influenzae Rd is shown. Filled circles (arrows) indicate Int1 lav compared to homologs in N. meningitidis serotype B and N. meningitidis serotype A, in ascending order of DNA similarity. Genes compared, in ascending order of DNA similarity, were tpiA, lig (lig-1 in N. meningitidis serotype B) dnaG, mutS, gyrA, rpoD, cysK, aroG, rpoB, recA, sucD, and ilvD (ilvD-1 in N. meningitidis serotype B). The sequences were compared using ClustalV (MEGALIGN).