Rapid Access: Justifying a Proposed Link between the Composition and Oxidative Capacity of Secretomes by Diverse Ascomycete Fungi
EMSL Project ID
48112
Abstract
Oxidized manganese, as both soluble Mn(III) and Mn(IV) oxides, is receiving increased attention as a dominant control on the degradation of lignin and decomposition of leaf litter. Both Mn(III) and Mn oxides are strong oxidants with the demonstrated capacity to degrade lignocellulose. While ascomycete fungi are considered an important route for carbon cycling in plant litter and soils, the mechanisms and regulation are poorly understood. Yet, the ability to oxidize Mn(II) has been demonstrated in a large diversity of ascomycete fungi. We have been investigating a diversity of ascomycete fungi that have the ability to both degrade cellulose and oxidize Mn(II) to Mn(III) and Mn oxides; yet whether or not these processes are linked is unknown. We have shown that for some organisms, Mn(II) is oxidized initially by extracellular superoxide (a reactive oxygen species – ROS) produced by transmembrane NADPH oxidases during cell differentiation. We have new preliminary evidence however suggesting that the pathway for Mn(II) oxidation varies with fungal species and changes as a function of nutrient conditions, switching from NADPH oxidase directed oxidation to oxidation by secreted proteins (presumably laccases). We propose that Mn(II) oxidation is a primary means of lignocellulose degradation by ascomycete fungi. We also propose that the mechanism of Mn(II) oxidation modulates between transmembrane and secreted enzymes in response to changing nutrient conditions, reflecting a dramatic shift in the oxidative capacity of the fungal secretome under changing biogeochemical conditions. Thus, the specific aim of this EMSL proposal is to obtain preliminary data supporting a link between the composition and oxidative capacity of ascomycete secretomes. We request use of the EMSL mass spectrometry facility to characterize the fungal secretome via LC-MS as a function of fungal species, time, and nutrient composition. This information will be compared to changes in the secretome oxidative capacity, particularly in terms of the generation of reactive oxygen species (ROS) and oxidation of both cellulose and Mn(II).This research will provide a unique and global proteome dataset of 24 fungal secretomes to interrogate and compare to the changes in oxidative capacity as it relates to ROS production, Mn(II) oxidation and cellulose degradation. Improving our mechanistic (molecular level) understanding of the enzymatic production of oxidants by fungi under varying biogeochemical conditions will improve model predictions of carbon degradation and CO2 emissions in a changing biogeochemical landscape, identify constraints on carbon sequestration within terrestrial ecosystems, introduce novel biofuel processes, and advance in situ bioremediation strategies – all of which are priority areas for the Department of Energy. We request Rapid Access support because there are two impending funding deadlines that could not be met if this request was submitted through the standard proposal process. The success of both of these funding requests is reliant upon first demonstrating changes in the secretome in conjunction with our previous observations of changes in cellulose and Mn(II) oxidation. We therefore submit this rapid access request to collect this crucial data that will greatly improve our potential for funding and continuation of this research.
Project Details
Project type
Limited Scope
Start Date
2013-08-01
End Date
2013-10-01
Status
Closed
Released Data Link
Team
Principal Investigator