Localization of a Microsporidia ADAM (A Disintegrin and Metalloprotease Domain) Protein and Identification of Potential Binding Partners.

<p>Microsporidia are spore-forming, obligate intracellular pathogens typically associated with opportunistic infections in immunocompromised individuals. Treatment options for microsporidia infections in humans are limited and additional research is necessary to create better therapeutic agents. For many pathogenic organisms, adhesion to the host cell surface is a prerequisite for tissue colonization and invasion. Our previous research has demonstrated a direct relationship between adherence of microsporidia spores to the surface of host cells and infectivity <em>in vitro</em>. In an effort to better understand adherence, we have turned our attention to determining what proteins may be involved in this process. Examination of the <em>Encephalitozoon cuniculi</em> genome database revealed a gene encoding a protein with sequence homology to members of the ADAM (a disintegrin and metalloprotease) family of type I transmembrane glycoproteins. The microsporidia ADAM (MADAM) protein is of interest because ADAMs are known to be involved in a variety of biological processes including cell adhesion, proteolysis, cell fusion, and signaling. The objectives for this study were to examine the localization of MADAM, analyze its potential involvement during adherence and/or host cell infection, and to identify potential binding partners or substrates. Through the use of immunoelectron transmission microscopy, we demonstrated that MADAM is localized to the surface exposed exospore, plasma membrane, and the polar sac-anchoring disk complex (a bell-shaped structure at the spore apex involved in the infection process). Location of MADAM within the exospore and polar sac-anchoring disk suggests that MADAM is in a position to facilitate spore adherence or host cell infection. Thus far, we have been unable to conclusively demonstrate that MADAM is involved in either event. Through the use of a yeast two-hybrid system, we were able to identify polar tube protein 3 (PTP3) as a potential binding partner or substrate for the MADAM protein. The interaction between MADAM and PTP3 was confirmed by <em>in vitro</em> co-immunoprecipitation. PTP3 is hypothesized to be involved in the process of polar tube extrusion by stabilizing the interaction between PTP1-PTP2 polymers. Further analysis of the interaction between MADAM and PTP3 may lead to a better understanding of the events that occur during polar tube extrusion.</p>

Name thesis:degree_name

PhD (Doctor of Philosophy)

Level thesis:degree_level

Dissertation - unrestricted

Discipline thesis:degree_discipline

Biomedical Sciences

Year dc:date.issued

2007

Author dc:creator

• Jolly, Carrie E.

• Encephalitozoon cuniculi
• Encephalitozoon intestinalis
• microsporidia
• yeast two-hybrid
• ADAM
• polar tube protein
• Amino Acids, Peptides, and Proteins
• Chemicals and Drugs
• Medicine and Health Sciences

Statement dc:rights

• Copyright by the authors.

Repository record dc:identifier

https://dc.etsu.edu/etd/2052

OAI identifier oai:identifier

oai:dc.etsu.edu:etd-3413