Mycobacteria Phagosome Maturation - Book Report/Review Example

Arrest of Mycobacterial Phagosome Maturation Is Caused by a Block in Vesicle Fusion between Stages Controlled by rab5 and rab7 The purpose of this research paper is to explore the relationship between the maturation of a phagosome to a phagolysosome and markers (specifically rab5 and rab7, small GTP-binding proteins) acquired during the maturation process from the endosomal compartment (Via et al, 1997). This is useful when considering pathogens that have and rely on the ability to live within the hostile environment of the phagosome which may rely on the blockage of these markers for their survival within the cell.

The use of Mycobacterium bovis here illustrates the relationship between these small GTP-binding proteins, the stages of phagosome maturation and how the two are associated.Approach This research uses a culture of macrophage-like cells (J774) cultured and kept in Cellgro, a medium with appropriate additives. These cells were then inoculated by exposure to the pathogen, M. bovis, incubated, lysed and then prepared for the investigation. After latex bead compartment isolation, flow cytometry and analysis of β-hexosaminidase activity, epiflourescence, laser scanning confocal and electron microscopy, the cells were then analysed for markers and phagosome maturation stage.

This was done by gel electrophoresis, GTP-binding overlay assay and Western Blot analysis (Via et al, 1997).Findings The findings found that initially, the phagosomal cells containing M. bovis BCG had a very similar GTP-binding process as those containing the latex beads (Via et al, 1997). The presence of M. bovis BCG caused an increase in the number of rab5 proteins accumulated by the cell, whereas the presence of the latex beads caused the reverse. Additionally, rab7 cannot be detected in those cells with MPC whereas LPC cells have fluctuating levels of rab 7 throughout the incubation period (Via et al, 1997).

This suggests that MPC gains the characteristics of the early endosome (in this case, the presence of rab5 proteins) but can remain isolated from the late endosomal cell characteristics (such as the lack of rab 7 proteins). These results illustrate not only the pattern that phagosome maturation takes but how M. bovis manipulates these maturation events to prevent lysis or expulsion from the host cell (Via et al, 1997).Related Research A study by Kitano, Nakaya, Nakamura, Nagata, & Matsuda. (2008) reinforces the importance of rab5 proteins in the endocytic pathway and the involvement of GTP-binding proteins in the maturation of the phagosome.

This research used newly developed imaging techniques to track the rab5 activity in a cell during engulfment of apoptopic thymocytes, finding that rab5 activity increased during the initial stages of phagosome development. This again supports the idea that M. bovis is using rab5 to mimic the early stages of the phagosome, which may be for the purpose of protection from the host cell.Conclusion Both of these research papers highlight the importance of GTP-binding proteins during the maturation of the phagosome and suggest some important issues to look for when investigating the pathogenic activity of certain species.

Additionally, both of the studies illustrate how phagosome maturation can be adjusted, which again is useful for future tests investigating the phagosomal transition to lysophagosome. By understanding the relationship between small GTP-binding proteins such as rab5 and rab7, these two papers will allow for further investigation into the other rab proteins (which were not studied extensively in the original paper) and the relationship between GTP-binding and disease.Works CitedKitano, M., Nakaya, M.

, Nakamura, T., Nagata, S., & Matsuda, M. (2008). Imaging of Rab5 activity identifies essential regulators for phagosome maturation. Nature, 453(7192), 241-245. doi:10.1038/nature06857Via, L. E., Deretic, D., Ulmer, R. J., Hibler, N. S., Huber, L. A., & Deretic, V. (1997). Arrest of Mycobacterial Phagosome Maturation Is Caused by a Block in Vesicle Fusion between Stages Controlled by rab5 and rab7. Journal of Biological Chemistry, 272(20), 13326 -13331. doi:10.1074/jbc.272.20.13326