Affiliation:
1. Department of Epidemiology and Public Health, Section of Vector Biology, Yale University School of Medicine, New Haven, Connecticut 06510
Abstract
ABSTRACT
Recent molecular characterization of various microbial genomes has revealed differences in genome size and coding capacity between obligate symbionts and intracellular pathogens versus free-living organisms. Multiple symbiotic microorganisms have evolved with tsetse fly, the vector of African trypanosomes, over long evolutionary times. Although these symbionts are indispensable for tsetse fecundity, the biochemical and molecular basis of their functional significance is unknown. Here, we report on the genomic aspects of the secondary symbiont
Sodalis glossinidius
. The genome size of
Sodalis
is approximately 2 Mb. Its DNA is subject to extensive methylation and based on some of its conserved gene sequences has an A+T content of only 45%, compared to the typically AT-rich genomes of endosymbionts. Sodalis also harbors an extrachromosomal plasmid about 134 kb in size. We used a novel approach to gain insight into
Sodalis
genomic contents, i.e., hybridizing its DNA to macroarrays developed for
Escherichia coli
, a closely related enteric bacterium. In this analysis we detected 1,800 orthologous genes, corresponding to about 85% of the
Sodalis
genome. The
Sodalis
genome has apparently retained its genes for DNA replication, transcription, translation, transport, and the biosynthesis of amino acids, nucleic acids, vitamins, and cofactors. However, many genes involved in energy metabolism and carbon compound assimilation are apparently missing, which may indicate an adaptation to the energy sources available in the only nutrient of the tsetse host, blood. We present gene arrays as a rapid tool for comparative genomics in the absence of whole genome sequence to advance our understanding of closely related bacteria.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
48 articles.
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