Strawberry fruit are a classic system for studies of the signaling between adjacent tissues as the expansion of the receptacle tissue is dependent on auxin released from the achenes. Within the last several years significant genetic resources for Fragaria and other members of the Rosaceae have been developed such that the diploid strawberry is now an important reference species for molecular characterization of studies of hormonal signaling within fruit tissues. Indole-3-acetic acid (IAA) is found in plants in both free and conjugated form. Among the conjugated IAA forms, there exists a unique class of proteins where IAA is a prosthetic group attached directly to the polypeptide structure. The first gene, for a bean protein with an IAA prosthetic group, has been cloned and a related protein and several smaller peptides were identified in Arabidopsis. The work in this project focuses on a unique IAA-modified protein found in the achenes and receptacle tissue of strawberry that has been shown to be the beta subunit of ATP synthase. This is the first IAA-protein with a predicted function to be described. While we have a general interest in understanding indoleacylation of plant proteins, the goals of the current project are focused on an indoleacyl-modified mitochondrial F1-ATP synthase from the diploid strawberry, Fragaria vesca. The project will focus on two main goals: 1. the use of mass spectral tools for determination of the site of IAA attachment; and 2. determination of the function of the IAA-modification on the ATP synthase.
Broader impacts of the project are as follows. This project will directly support one postdoctoral scientist and one graduate student who will be involved in this project that requires, in addition to plant biochemistry and molecular biology, specific expertise in the use of modern techniques of protein and small molecule mass spectrometric analysis to answer fundamental questions in plant biology. It will also provide a resource for others interested in studies of novel native modified peptides and studies of plant hormone metabolism, either as visitors to the host laboratory or by transfer of the methods to their own facility.
