Machinery for fungal heme acquisition

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Iron, specifically in the form of heme, is vital for aerobic organisms.
• While heme biosynthesis is well-understood, mechanisms for acquiring external heme are less clear.
• Fungal pathogens require heme for colonization and survival.

Purpose of the Study:

• To elucidate novel proteins and mechanisms involved in exogenous heme uptake in Schizosaccharomyces pombe.
• To investigate the genetic basis of heme assimilation in a model yeast system.
• To understand how fungi acquire essential heme from their environment.

Main Methods:

• Utilizing Schizosaccharomyces pombe as a model organism with blocked heme biosynthesis.
• Employing genetic approaches to identify and characterize heme uptake pathways.
• Investigating the roles of Shu1 and Str3 in heme assimilation.

Main Results:

• Identified two independent heme uptake systems in S. pombe, mediated by Shu1 and Str3.
• Shu1 captures cell-surface heme, facilitating vacuolar internalization via ubiquitination and ESCRT.
• Str3 functions as a plasma membrane transporter for heme import, particularly when Shu1 is absent.

Conclusions:

• The discovery of Shu1 and Str3 pathways provides novel insights into fungal heme assimilation.
• These findings highlight essential biological processes for fungal niche colonization.
• Understanding heme acquisition mechanisms can inform strategies against fungal pathogens.