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Title: INDOLEACETIC ACID AS A PROTEIN PROSTHETIC GROUP IN PHASEOLUS VULGAR IS

Author
item WALZ, ALEXANDER - UNIV. OF MINNESOTA
item PARK, SEIJIN - UNIV. OF MINNESOTA
item Slovin, Janet
item LUDWIG-MULLER, JUTTA - TECHNISCHE UNIV, GERMANY

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/2/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A diverse number of prosthetic groups are known to be covalently attached to proteins as postranslational modifications. In plants, glycoproteins, lipo-, phospho-, hemo-, flavo- and metallo-proteins all represent examples of such conjugated proteins. We have reported that a group of proteins with molecular masses of 17-60 kD exists in bean (Phaseolus vulgaris) that have a prosthetic group consisting of the phytohormone indole-3-acetic acid (IAA). The existence of these proteins in plants suggests an additional mechanism for biological responses to auxin. The gene for the most abundant of these proteins, designated as iap1, (GenBank Acc. No. AF293023) was isolated, cloned and sequenced. The 957 bp open reading frame encodes a polypeptide with a predicted molecular mass of 35 kDa. That runs anomalously as a 42 kDa protein on SDS-PAGE. MALDI-TOF MS, expression in E. coli and in vitro transcription and translation results confirmed the identity of this protein. High expression of RNA and protein occurs late during seed development and the protein undergoes rapid degradation during germination. An IAA-protein was immunolocalized to the root meristem and outer cell regions of the cotyledons and seed radicle in Arabidopsis. Crossreacting proteins were also found in the outer cell layers of cantaloupe and tomato fruit and in seed proteins of different plant species. GC-MS analysis confirmed the presence of IAA covalently bound to protein in Arabidopsis. Protein modification by IAA may present an additional mechanism for auxin induced protein turnover in planta and may explain other processes involved in growth and development. Supported by National Science Foundation grant IBN97-23999.