Nature 364, 161 - 164 (08 July 1993); doi:10.1038/364161a0

Arabidopsis auxin-resistance gene AXR1 encodes a protein related to ubiquitin-activating enzyme E1

H. M. Ottoline Leyser, Cynthia A. Lincoln^*, Candace Timpte, Douglas Lammer, Jocelyn Turner & Mark Estelle

Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
^*Present address: USDA Plant Gene Expression Center, 800 Buchanan St. Albany, California 94710, USA.
^†To whom correspondence should be addressed.

THE plant hormone auxin has a central role in many aspects of plant growth and development^1,2. By screening for mutants of Arabidopsis that are resistant to exogenous auxin, we have identified several genes that are required for normal auxin response³. One of these genes, AXR1, is defined by recessive mutations that confer auxin resistance to the roots, rosettes and inflorescences of mutant plants^4–6. In addition, axr1 mutants display a variety of morphological defects that are consistent with a reduction in auxin sensitivity⁵. Here we isolate the AXR1 gene using a map-based approach and report that AXR1 encodes a new protein with significant sequence similarity to the ubiquitin-activating enzyme E1. The AXR1 protein is highly diverged from previously characterized E1 enzymes, however, and lacks a key cysteine residue that is essential for E1 activity⁷. AXR1 may therefore define a new class of enzymes in the ubiquitin pathway or it may have a novel function in cellular regulation which is unrelated to ubiquitin conjugation.

References

1.	Evans, M. L. in Encyclopedia of Plant Physiology 10 (ed. Scott, T. K.) 23−79 (1985).
2.	Davies, P. J. in Plant Hormones and their Role in Plant Growth and Development (ed. Davies, P. J.) 1−11 (1988). | ChemPort |
3.	Estelle, M. BioEssays 14, 439−444 (1992). | Article | PubMed | ChemPort |
4.	Estelle, M. & Somerville, C. R. Molec. gen. Genet. 206, 200−206 (1987). | Article | ChemPort |
5.	Lincoln, C. et al. Plant Cell 2, 1071−1080 (1990). | Article | PubMed | ISI | ChemPort |
6.	Lincoln, C. & Estelle, M. Iowa Acad. Sci. 98, 68−71 (1991). | ChemPort |
7.	Hatfield, P. M. & Vierstra, R. D. J. biol. Chem. 267, 14799−14803 (1992). | PubMed | ISI | ChemPort |
8.	Ward, E. R. & Jen, G. C. Plant molec. Biol. 14, 561−568 (1990). | ChemPort |
9.	Olszewski, N. E. et al. Nucleic Acids Res. 16, 10765−10782 (1988). | PubMed | ISI | ChemPort |
10.	Valvekens, D. et al. Proc. natn. Acad. Sci. 85, 5536−5540 (1988). | ChemPort |
11.	Devereaux, J., Haeberli, P. & Smithies, O. Nucleic Acids Res. 12, 387−394 (1984). | PubMed | ISI | ChemPort |
12.	Handley, P. M. et al. Proc. natn. Acad. Sci. U.S.A. 88, 258−262 (1991). | ChemPort |
13.	McGrath, J. P., Jentsch, S. & Varshavsky, A. EMBO J. 10, 227−236 (1991). | PubMed | ISI | ChemPort |
14.	Hatfield, P. M., Callis, J. & Vierstra, R. J. biol. Chem. 265, 15813−15817 (1990). | PubMed | ISI | ChemPort |
15.	Finley, K. & Chau, V. A. Rev. Cell Biol. 7, 25−69 (1991).
16.	Cenciarelli, C. et al. Science 257, 795−797 (1992). | PubMed | ISI | ChemPort |
17.	Mori, S., Heldin, C.-H. & Claesson-Welsh, L. J. biol. Chem. 267, 6429−6434 (1992). | PubMed | ISI | ChemPort |
18.	Paolini, R. & Kinet J.-P. EMBO J. 12, 779−786 (1993). | PubMed | ISI | ChemPort |
19.	Suiter, K. A., Wendel, J. F. & Case, J. S. J. Heredity 74, 203−204 (1983). | ChemPort |
20.	Chang, C. et al. Proc. natn. Acad. Sci. U.S.A. 85, 6856−6860 (1983).
21.	Nam, H-G. et al. Plant Cell 1, 699−705 (1989). | Article | PubMed | ISI | ChemPort |
22.	Dellaporta, S. L. et al. Plant molec. Biol. Rep. 1, 181−192 (1983).
23.	Sambrook, J. et al. Molecular Cloning: A Laboratory Manual (Cold Spring Harbor Press New York, 1989).
24.	Nairn, C. J. et al. Gene 65, 247−257 (1988). | Article | PubMed | ISI | ChemPort |
25.	Puissant, C. & Houdebine, L-M. Biotechniques 8, 148−149 (1990). | PubMed | ISI | ChemPort |