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Aspergillus fumigatus arp1 modulates conidial pigmentation and complement deposition
H F Tsai1, R G Washburn, Y C Chang
1Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA.
Molecular Microbiology
|January 31, 1998
Summary
The Aspergillus fumigatus arp1 gene controls conidial pigment and complement deposition. Disruption of arp1 leads to reddish-pink conidia with increased C3 binding, impacting opsonophagocytosis.
Area of Science:
- Mycology
- Immunology
- Molecular Biology
Background:
- Aspergillus fumigatus causes invasive pulmonary aspergillosis in immunocompromised individuals.
- Conidia are the infectious fungal structures inhaled by the host.
- Opsonophagocytosis, enhanced by complement deposition, aids conidial clearance.
Purpose of the Study:
- To investigate the role of conidial pigmentation in Aspergillus fumigatus immune evasion.
- To identify genes involved in regulating conidial color and complement binding.
Main Methods:
- Analysis of conidial color mutants and their C3 binding capacity.
- Complementation of a reddish-pink mutant using a cosmid clone.
- DNA sequencing and characterization of the identified gene, arp1.
- Northern hybridization to assess arp1 expression during conidiation.
- Gene disruption to confirm arp1 function.
Main Results:
- Conidial color mutants showed increased C3 binding compared to wild type.
- A 3.3 kb DNA fragment containing the arp1 gene restored bluish-green pigmentation and normal C3 binding.
- Arp1 encodes a putative 168-amino acid protein similar to scytalone dehydratase.
- Arp1 expression is developmentally regulated during conidiation.
- Disruption of arp1 resulted in reddish-pink conidia with elevated C3 binding.
Conclusions:
- The arp1 gene modulates Aspergillus fumigatus conidial pigmentation.
- Arp1 influences complement deposition on conidia.
- These findings suggest a link between fungal pigment and host immune response evasion.