Figure 4.

Essential ORFs of H. influenzae. Five chromosomal segments are shown. ORFs with essential functions are shown in black, ORFs that are nonessential are shown in white, and ORFs in which mutations produce growth attenuation are shown in gray. The direction of transcription for each ORF is shown along with the TIGR designation below the ORF and the closest homologue above the ORF. Conserved hypothetical ORFs of unknown function are designated CH. [*, Essential ORFs that can sustain a highly limited number of discrete insertions (<2/kbp).]