Abstract
Complete genome DNA sequence and analysis is presented for
Wolbachia,
the obligate alpha-proteobacterial endosymbiont required for fertility and survival of the human filarial parasitic nematode
Brugia malayi.
Although, quantitatively, the genome is even more degraded than those of closely related
Rickettsia
species,
Wolbachia
has retained more intact metabolic pathways. The ability to provide riboflavin, flavin adenine dinucleotide, heme, and nucleotides is likely to be
Wolbachia
's principal contribution to the mutualistic relationship, whereas the host nematode likely supplies amino acids required for
Wolbachia
growth. Genome comparison of the
Wolbachia
endosymbiont of
B. malayi
(
w
Bm) with the
Wolbachia
endosymbiont of
Drosophila melanogaster
(
w
Mel) shows that they share similar metabolic trends, although their genomes show a high degree of genome shuffling. In contrast to
w
Mel,
w
Bm contains no prophage and has a reduced level of repeated DNA. Both
Wolbachia
have lost a considerable number of membrane biogenesis genes that apparently make them unable to synthesize lipid A, the usual component of proteobacterial membranes. However, differences in their peptidoglycan structures may reflect the mutualistic lifestyle of
w
Bm in contrast to the parasitic lifestyle of
w
Mel. The smaller genome size of
w
Bm, relative to
w
Mel, may reflect the loss of genes required for infecting host cells and avoiding host defense systems. Analysis of this first sequenced endosymbiont genome from a filarial nematode provides insight into endosymbiont evolution and additionally provides new potential targets for elimination of cutaneous and lymphatic human filarial disease.
Analysis of this
Wolbachia
genome, which resides within filarial parasites, offers insight into endosymbiont evolution and the promise of new strategies for the elimination of human filarial disease