Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Minimization of the Legionella pneumophila genome reveals chromosomal regions involved in host range expansion

Tamara J. O'Connor, Yewande Adepoju, Dana Boyd and Ralph R. Isberg
Proceedings of the National Academy of Sciences of the United States of America
Vol. 108, No. 36 (September 6, 2011), pp. 14733-14740
Stable URL: http://www.jstor.org/stable/27979370
Page Count: 8
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Preview not available

Abstract

Legionella pneumophila is a bacterial pathogen of amoebae and humans. Intracellular growth requires a type IVB secretion system that translocates at least 200 different proteins into host cells. To distinguish between proteins necessary for growth in culture and those specifically required for intracellular replication, a screen was performed to identify genes necessary for optimal growth in nutrient-rich medium. Mapping of these genes revealed that the L. pneumophila chromosome has a modular architecture consisting of several large genomic islands that are dispensable for growth in bacteriological culture. Strains lacking six of these regions, and thus 18.5% of the genome, were viable but required secondary point mutations for optimal growth. The simultaneous deletion of five of these genomic loci had no adverse effect on growth of the bacterium in nutrient-rich media. Remarkably, this minimal genome strain, which lacked 31% of the known substrates of the type IVB system, caused only marginal defects in intracellular growth within mouse macrophages. In contrast, deletion of single regions reduced growth within amoebae. The importance of individual islands, however, differed among amoebal species. The host-specific requirements of these genomic islands support a model in which the acquisition of foreign DNA has broadened the L. pneumophila host range.

Page Thumbnails

  • Thumbnail: Page 
14733
    14733
  • Thumbnail: Page 
14734
    14734
  • Thumbnail: Page 
14735
    14735
  • Thumbnail: Page 
14736
    14736
  • Thumbnail: Page 
14737
    14737
  • Thumbnail: Page 
14738
    14738
  • Thumbnail: Page 
14739
    14739
  • Thumbnail: Page 
14740
    14740