The insect endosymbiont Sodalis glossinidius utilizes a type III secretion system for cell invasion

C Dale, Simon Young, D T Haydon, S C Welburn

Research output: Contribution to journalArticlepeer-review

197 Citations (Scopus)

Abstract

Sodalis glossinidius is a maternally transmitted secondary endosymbiont residing intracellularly in tissues of the tsetse flies, Glossina spp. In this study, we have used Tn5 mutagenesis and a negative selection procedure to derive a S, glossinidius mutant that is incapable of invading insect cells in vitro and is aposymbiotic when microinjected into tsetse, This mutant strain harbors Tn5 integrated into a chromosomal gene sharing high sequence identity with a type III secretion system invasion gene (invC) previously identified in Salmonella enterica. With the use of degenerate PCR, we have amplified a further six Sodalis inv/spa genes sharing high sequence identity with type III secretion system genes encoded by Salmonella pathogenicity island 1. Phylogenetic: reconstructions based on the inv/spa genes of Sodalis and other members of the family Enterobacteriaceae have consistently identified a well-supported clade containing Sodalis and the enteric pathogens Shigella and Salmonella, These results suggest that Sodalis may have evolved from an ancestor with a parasitic intracellular lifestyle, possibly a latter-day entomopathogen. These observations lend credence to a hypothesis suggesting that vertically transmitted mutualistic endosymbionts evolve from horizontally transmitted parasites through a parasitism-mutualism continuum.

Original languageEnglish
Pages (from-to)1883-1888
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume98
Issue number4
Publication statusPublished - 13 Feb 2001

Keywords

  • TSETSE-FLIES
  • WIGGLESWORTHIA-GLOSSINIDIA
  • PATHOGENICITY ISLANDS
  • SALMONELLA-ENTERICA
  • BACTERIAL PATHOGENS
  • EVOLUTION
  • TRANSMISSION
  • PHYLOGENY
  • SYMBIONT
  • PROTEINS

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