Cellular Copper Import Mechanisms via Secreted Cuproproteins: Exploring Metal Homeostasis in Pseudogymnoascus destructans

This thesis investigates the metal stress response of the fungal pathogen Pseudogymnoascus destructans (Pd), which causes White-Nose Syndrome in bats. Special emphasis is placed on understanding how cellular metal status effects Bim1-like Proteins (BLPs) and high-affinity copper transporters (CTR proteins) transcription levels. These two families of copper-binding proteins have been shown to facilitate copper uptake, which is critical for fungal growth, survival, and virulence, especially in the nutrient-restrictive conditions encountered during host colonization niche. Kinetic growth assays demonstrated a dose-dependent relationship between fungal growth and copper concentrations, where copper acted both as a growth enhancer at lower concentrations and a stressor at higher levels. Iron supplementation similarly influenced fungal growth, while the presence of copper and iron chelators, such as bathocuproinedisulfonic acid (BCS) and bathophenanthroline disulfonate (BPS), restricted growth, underscoring the dependency of P. destructans on these metals. Differential gene expression analyses further highlighted copper-responsive pathways that modulate copper transport and oxidative stress responses. Inductively coupled plasma mass spectrometry (ICP-MS) data revealed copper homeostasis adjustments, particularly under copper- or iron-limiting conditions. Microscopy with Phen Green FL provided visualization of intracellular copper dynamics, where copper chelation and supplementation induced marked changes in fluorescence, reflecting variations in intracellular copper levels. These findings support a model where BLPs, by scavenging copper and interfacing with CTR transporters, play a pivotal role in maintaining copper homeostasis. This function is essential for overcoming metal-limiting environments imposed by the host during infection. Collectively, the study provides insights into the metal acquisition strategies of P. destructans, contributing to broader understanding of fungal pathogenesis and opening avenues for anti-fungal strategies targeting metal homeostasis pathways.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Biochemistry

Grantor

Texas State University

Year dc:date.issued

2024

Author dc:creator

• Gonzalez, Daniella

Advisor dc:contributor.advisor

• Peterson, Ryan

Committee members dc:contributor.committeemember

• Lewis, Lysle Kevin
• Lu, Yuan

• copper
• fungal pathogen
• copper transporter
• CTR
• BLP
• metal-homeostasis
• white-nose syndrome
• WNS
• bats
• infectious disease

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10877/20119

OAI identifier oai:identifier

oai:digital.library.txst.edu:10877/20119