Bacteria Provide Example of One of Nature's First Immune Systems, Research Shows
ScienceDaily (Dec. 30, 2010) — Studying how bacteria incorporate foreign DNA from invading viruses into their own regulatory processes, Thomas Wood, professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, is uncovering the secrets of one of nature's most primitive immune systems.
Single gram-negative Escherichia coli bacterium. Studying how bacteria incorporate foreign DNA from invading viruses into their own regulatory processes, Thomas Wood, professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, is uncovering the secrets of one of nature's most primitive immune systems. (Credit: Janice Haney Carr)
His findings, which appear in Nature Communications, a multidisciplinary publication dedicated to research in all areas of the biological, physical and chemical sciences, shed light on how bacteria have throughout the course of millions of years developed resistance to antibiotics by co-opting the DNA of their natural enemies -- viruses.
The battle between bacteria and bacteria-eating viruses, Wood explains, has been going on for millions of years, with viruses attempting to replicate themselves by -- in one approach -- invading bacteria cells and integrating themselves into the chromosomes of the bacteria. When this happens a bacterium makes a copy of its chromosome, which includes the virus particle. The virus then can choose at a later time to replicate itself, killing the bacterium -- similar to a ticking time bomb, Wood says.
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Cryptic prophages help bacteria cope with adverse environments
Xiaoxue Wang, Younghoon Kim, Qun Ma, Seok Hoon Hong, Karina Pokusaeva, Joseph M. Sturino & Thomas K. Wood
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Nature Communications 1, Article number: 147 doi:10.1038/ncomms1146
Received 26 May 2010 Accepted 25 November 2010 Published 21 December 2010
Phages are the most abundant entity in the biosphere and outnumber bacteria by a factor of 10. Phage DNA may also constitute 20% of bacterial genomes; however, its role is ill defined. Here, we explore the impact of cryptic prophages on cell physiology by precisely deleting all nine prophage elements (166 kbp) using Escherichia coli. We find that cryptic prophages contribute significantly to resistance to sub-lethal concentrations of quinolone and β-lactam antibiotics primarily through proteins that inhibit cell division (for example, KilR of rac and DicB of Qin). Moreover, the prophages are beneficial for withstanding osmotic, oxidative and acid stresses, for increasing growth, and for influencing biofilm formation. Prophage CPS-53 proteins YfdK, YfdO and YfdS enhanced resistance to oxidative stress, prophages e14, CPS-53 and CP4-57 increased resistance to acid, and e14 and rac proteins increased early biofilm formation. Therefore, cryptic prophages provide multiple benefits to the host for surviving adverse environmental conditions.
Subject terms: Biological sciences, Evolution, Microbiology, Molecular biology
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