Cloning and analysis of cDNA encoding an elongation factor 1 alpha from the dimorphic fungus Histoplasma capsulatum

Area of Science:

• Molecular biology
• Mycology
• Genetics

Background:

• Histoplasma capsulatum (Hc) is a dimorphic fungus and a significant human pathogen.
• Understanding the genetic makeup of Hc is crucial for studying its virulence and developing targeted therapies.

Purpose of the Study:

• To isolate and characterize the cDNA encoding translation elongation factor 1 alpha (EF-1 alpha) from Histoplasma capsulatum.
• To analyze the gene's structure, expression, and evolutionary relationships within fungi.

Main Methods:

• Screening a Hc cDNA library using the tef1 gene probe from Mucor racemosus.
• Sequencing the longest isolated clone (1.96 kb).
• Southern blot analysis to determine gene copy number and Northern blot analysis to assess transcript size and expression in different fungal forms.

Main Results:

• Ten independent clones encoding EF-1 alpha were isolated, with the longest clone sequenced.
• The Hc tef1 gene exists as a single copy and produces a single transcript of approximately 2300 nucleotides in both yeast and mold forms.
• The deduced Hc EF-1 alpha protein shows highest similarity to proteins from filamentous ascomycetes, suggesting a close evolutionary relationship.

Conclusions:

• The characterization of the Hc EF-1 alpha gene provides insights into the molecular biology of Histoplasma capsulatum.
• Phylogenetic analysis places Hc closer to filamentous ascomycetes than to budding yeasts like Saccharomyces cerevisiae.
• This study contributes to understanding fungal evolution and the genetic basis of dimorphism in pathogenic fungi.