CTXφ Bacteriophage

From MicrobeWiki, the student-edited microbiology resource

Overview

Figure 1: Filamentous phage(s) under an electron microscope (left), an artist's rendition, and some computer-generated models of varying proteins found in the head, neck, and tail fibers.[1] From Gagic D. et al. (2016).

The CTXφ bacteriophage (or sometimes written as CTXphi bacteriophage) is a lysogenic, filamentous, single-stranded DNA (ssDNA) phage that is responsible for turning the previously non-infectious Vibrio cholerae into a highly pathogenic microbe that causes disease in humans.[2],[3], [4]

Genetic Material

Figure 2: A schematic representation of the CTXφ genome.[4] From Boyd (2010).

The CTXφ phage can be identified in its host in both its replicative form (when the bacteriophage is in lysogeny, or the lytic cycle), and in its non-replicative form, which is most common. This phage, when in its lysogenic cycle, integrates its own genetic material in such a way as to form the most stable lysogens.[4]


Infection, Replication & Lysing of Host Cell

In a process known as lysogenic phage conversion, the CTXφ bacteriophage integrates, among others, its ctxAB genes into its host, Vibrio cholerae. The ctxAB genes code for a type of exotoxin, called Cholera toxin or just "CT," that causes V. cholerae to switch from being nonpathogenic to highly virulent. It is also the primary cause of the large amounts of diarrhea—cholera's main symptom.[4]

Figure 3: The life cycle of the CTXφ Bacteriophage with Vibrio cholerae as its host.



Other examples:
Bold
Italic
Subscript: H2O
Superscript: Fe3+


CT & non-CT Toxins

The CTXφ phage contains both types of exotoxins.

CT Toxins


Non-CT Toxins


Conclusion

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References

  1. ↑ Gagic, D., Ciric M., Wen W., Ng F., Rakonjac J. (2016). "Exploring the Secretomes of Microbes and Microbial Communities Using Filamentous Phage Display." Frontiers in Microbiology, 7:429. https://doi.org/10.3389/fmicb.2016.00429.
  2. ↑ Davis, B. M., Kimsey, H. H., Chang, W., & Waldor, M. K. (1999). "The Vibrio cholerae O139 Calcutta bacteriophage CTXφ is infectious and encodes a novel repressor." Journal of Bacteriology, 181(21), 6779-6787. https://www.frontiersin.org/articles/10.3389/fmicb.2016.00429/full
  3. ↑ Ochman, H., Lawrence, J. & Groisman, E. (2000). "Lateral gene transfer and the nature of bacterial innovation." Nature, 405, 299–304. https://doi.org/10.1038/35012500.
  4. ↑ 4.0 4.1 4.2 4.3 Boyd, E. F. (2010). "Efficiency and specificity of CTXphi chromosomal integration: dif makes all the difference." Proceedings of the National Academy of Sciences of the United States of America, 107(9), 3951–3952. https://doi.org/10.1073/pnas.1000310107


Edited by Tara Cerny, student of Joan Slonczewski for BIOL 116 Information in Living Systems, 2019, Kenyon College.

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