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Title: A GENE ENCODING A PROTEIN MODIFIED BY THE PHYTOHORMONE INDOLEACETIC ACID

Author
item WALZ, ALEXANDER - UNIVERSITY OF MINNESOTA
item PARK, SEIJIN - UNIVERSITY OF MINNESOTA
item MOMONOKI, YOSHIE - TOKYO UNIV OF AGRICULTURE
item Slovin, Janet
item LUDWIG-MUELLER, JUTTA - TECHNISCHE UNIV DRESDEN
item COHEN, JERRY - UNIVERSITY OF MINNESOTA

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: We have previously reported that a group of proteins with molecular masses of 17-60 kDa from bean (Phaseolus vulgaris) seeds were posttranslationally modified by IAA. The physiological significance of this modification is unknown and is currently being investigated. After internal microsequencing of the most abundant 42 kDa protein covalently modified by IAA, specific probes were made to screen a cDNA library from 3 week old bean seeds. The gene 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. However, this polypeptide runs anomalously as a 42 kDa protein on SDS-PAGE. Results from MALDI-TOF MS, expression in E. coli and in vitro transcription and translation confirmed this observation. Southern hybridization indicated that a single copy gene encodes this IAA modified protein. High expression at the RNA and protein levels occurs late during seed development. In contrast, the protein undergoes rapid degradation during germination. In Arabidopsis, the protein was immunolocalized to the root meristem and outer cell regions of the cotyledons and seed radicle. GC-MS analysis of the partially purified protein confirmed the presence of IAA covalently bound, indicating the presence of IAA proteins in dicots other than bean. Protein modification by IAA is an additional mechanism for auxin turnover in planta and may explain other processes involved in growth and development.