| Structural highlights
Function
[MYC3_ARATH] Transcription factor involved in tryptophan, jasmonic acid (JA) and other stress-responsive gene regulation. With MYC2 and MYC4, controls additively subsets of JA-dependent responses. Can form complexes with all known glucosinolate-related MYBs to regulate glucosinolate biosynthesis. Binds to the G-box (5'-CACGTG-3') of promoters. Activates multiple TIFY/JAZ promoters.[1] [2] [3] [4] [5] [TIF7_ARATH] Repressor of jasmonate responses negatively regulated by the proteasome in an SCF(COI1) E3 ubiquitin-protein ligase complex-dependent manner. Jasmonoyl-isoleucine (JA-Ile) specifically promotes COI1-TIFY7/JAZ9 interaction.[6]
Publication Abstract from PubMed
The plant hormone jasmonate plays crucial roles in regulating plant responses to herbivorous insects and microbial pathogens and is an important regulator of plant growth and development. Key mediators of jasmonate signalling include MYC transcription factors, which are repressed by jasmonate ZIM-domain (JAZ) transcriptional repressors in the resting state. In the presence of active jasmonate, JAZ proteins function as jasmonate co-receptors by forming a hormone-dependent complex with COI1, the F-box subunit of an SCF-type ubiquitin E3 ligase. The hormone-dependent formation of the COI1-JAZ co-receptor complex leads to ubiquitination and proteasome-dependent degradation of JAZ repressors and release of MYC proteins from transcriptional repression. The mechanism by which JAZ proteins repress MYC transcription factors and how JAZ proteins switch between the repressor function in the absence of hormone and the co-receptor function in the presence of hormone remain enigmatic. Here we show that Arabidopsis MYC3 undergoes pronounced conformational changes when bound to the conserved Jas motif of the JAZ9 repressor. The Jas motif, previously shown to bind to hormone as a partly unwound helix, forms a complete alpha-helix that displaces the amino (N)-terminal helix of MYC3 and becomes an integral part of the MYC N-terminal fold. In this position, the Jas helix competitively inhibits MYC3 interaction with the MED25 subunit of the transcriptional Mediator complex. Our structural and functional studies elucidate a dynamic molecular switch mechanism that governs the repression and activation of a major plant hormone pathway.
Structural basis of JAZ repression of MYC transcription factors in jasmonate signalling.,Zhang F, Yao J, Ke J, Zhang L, Lam VQ, Xin XF, Zhou XE, Chen J, Brunzelle J, Griffin PR, Zhou M, Xu HE, Melcher K, He SY Nature. 2015 Aug 10. doi: 10.1038/nature14661. PMID:26258305[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Smolen GA, Pawlowski L, Wilensky SE, Bender J. Dominant alleles of the basic helix-loop-helix transcription factor ATR2 activate stress-responsive genes in Arabidopsis. Genetics. 2002 Jul;161(3):1235-46. PMID:12136026
- ↑ Cheng Z, Sun L, Qi T, Zhang B, Peng W, Liu Y, Xie D. The bHLH transcription factor MYC3 interacts with the Jasmonate ZIM-domain proteins to mediate jasmonate response in Arabidopsis. Mol Plant. 2011 Mar;4(2):279-88. doi: 10.1093/mp/ssq073. Epub 2011 Jan 17. PMID:21242320 doi:http://dx.doi.org/10.1093/mp/ssq073
- ↑ Niu Y, Figueroa P, Browse J. Characterization of JAZ-interacting bHLH transcription factors that regulate jasmonate responses in Arabidopsis. J Exp Bot. 2011 Mar;62(6):2143-54. doi: 10.1093/jxb/erq408. Epub 2011 Feb 14. PMID:21321051 doi:http://dx.doi.org/10.1093/jxb/erq408
- ↑ Fernandez-Calvo P, Chini A, Fernandez-Barbero G, Chico JM, Gimenez-Ibanez S, Geerinck J, Eeckhout D, Schweizer F, Godoy M, Franco-Zorrilla JM, Pauwels L, Witters E, Puga MI, Paz-Ares J, Goossens A, Reymond P, De Jaeger G, Solano R. The Arabidopsis bHLH transcription factors MYC3 and MYC4 are targets of JAZ repressors and act additively with MYC2 in the activation of jasmonate responses. Plant Cell. 2011 Feb;23(2):701-15. doi: 10.1105/tpc.110.080788. Epub 2011 Feb 18. PMID:21335373 doi:http://dx.doi.org/10.1105/tpc.110.080788
- ↑ Schweizer F, Fernandez-Calvo P, Zander M, Diez-Diaz M, Fonseca S, Glauser G, Lewsey MG, Ecker JR, Solano R, Reymond P. Arabidopsis basic helix-loop-helix transcription factors MYC2, MYC3, and MYC4 regulate glucosinolate biosynthesis, insect performance, and feeding behavior. Plant Cell. 2013 Aug;25(8):3117-32. doi: 10.1105/tpc.113.115139. Epub 2013 Aug, 13. PMID:23943862 doi:http://dx.doi.org/10.1105/tpc.113.115139
- ↑ Chung HS, Howe GA. A critical role for the TIFY motif in repression of jasmonate signaling by a stabilized splice variant of the JASMONATE ZIM-domain protein JAZ10 in Arabidopsis. Plant Cell. 2009 Jan;21(1):131-45. doi: 10.1105/tpc.108.064097. Epub 2009 Jan 16. PMID:19151223 doi:http://dx.doi.org/10.1105/tpc.108.064097
- ↑ Zhang F, Yao J, Ke J, Zhang L, Lam VQ, Xin XF, Zhou XE, Chen J, Brunzelle J, Griffin PR, Zhou M, Xu HE, Melcher K, He SY. Structural basis of JAZ repression of MYC transcription factors in jasmonate signalling. Nature. 2015 Aug 10. doi: 10.1038/nature14661. PMID:26258305 doi:http://dx.doi.org/10.1038/nature14661
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