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Structural highlights

Function

CRY2_ARATH Photoreceptor that mediates primarily blue light inhibition of hypocotyl elongation and photoperiodic control of floral initiation, and regulates other light responses, including circadian rhythms, tropic growth, stomata opening, guard cell development, root development, bacterial and viral pathogen responses, abiotic stress responses, cell cycles, programmed cell death, apical dominance, fruit and ovule development, seed dormancy, and magnetoreception. Photoexcited cryptochromes interact with signaling partner proteins to alter gene expression at both transcriptional and post-translational levels and, consequently, regulate the corresponding metabolic and developmental programs (PubMed:21841916). Blue-light absorbing flavoprotein that activates reversible flavin photoreduction via an electron transport chain comprising a tryptophan triad (W-321, W-374 and W-397), or via an alternative electron transport that involves small metabolites, including NADPH, NADH, and ATP. The half-life of the activated signaling state is about 16 minutes (PubMed:25428980, PubMed:23398192). Perceives low blue light (LBL) and responds by directly contacting two bHLH transcription factors, PIF4 and PIF5, at chromatin on E-box variant 5'-CA[CT]GTG-3' to promote their activity and stimulate specific gene expression to adapt global physiology (e.g. hypocotyl elongation and hyponastic growth in low blue light) (PubMed:26724867, PubMed:19558423). In response to blue light, binds to CIB proteins (e.g. BHLH63/CIB1 and BHLH76/CIB5) to activates transcription and floral initiation (PubMed:24130508). Mediates blue light-induced gene expression, floral initiation and hypocotyl elongation through the interaction with SPA1 that prevents formation of SPA1/COP1 complex but stimulates COP1 binding, and thus inhibits COP1-mediated degradation of transcription factors (e.g. CO and HY5) (PubMed:21514160, PubMed:21511872, PubMed:16093319). Promotes flowering time in continuous light (LL) (PubMed:21296763). Involved in shortening the circadian clock period, especially at 27 degrees Celsius, in blue light (BL). Required to maintain clock genes expression rhythm (PubMed:23511208). Triggers nuclear accumulation of ROS in response to blue light illumination (PubMed:26179959). Involved in blue light-dependent stomatal opening, transpiration and inhibition of stem and root growth, probably by regulating abscisic acid (ABA) (PubMed:22147516, PubMed:16093319, PubMed:16703358, PubMed:9482948, PubMed:9565033). Regulates the timing of flowering by promoting the expression of 'FLOWERING LOCUS T' (FT) in vascular bundles. Negatively regulated by 'FLOWERING LOCUS C' (FLC) (PubMed:14605222, PubMed:17259260). General positive regulator of reversible low light-induced chromatin decompaction (PubMed:20935177). Involved in triggering chromatin decondensation during floral transition (PubMed:17470059). Together with phototropins, involved in phototropism regulation by various blue light fluence; blue light attenuates phototropism in high fluence rates (100 umol.m-2.s-1) but enhances phototropism in low fluence rates (<1.0 umol.m-2.s-1) (PubMed:12857830). The effect of near-null magnetic field on flowering is altered by changes of blue light cycle and intensity in a CRY1/CRY2-dependent manner (PubMed:26095447). Involved in the strigolactone signaling that regulates hypocotyl growth in response to blue light (PubMed:24126495).^{[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23]} Confers resistance to turnip crinkle virus (TCV) by preventing COP1-mediated proteasome-mediated degradation of RPP8/HRT, thus promoting its stability in light. Exposure to darkness or blue-light induces degradation of CRY2, and in turn of RPP8/HRT, resulting in susceptibility to TCV.^[24]

References

1. ↑ Whippo CW, Hangarter RP. Second positive phototropism results from coordinated co-action of the phototropins and cryptochromes. Plant Physiol. 2003 Jul;132(3):1499-507. doi: 10.1104/pp.102.018481. PMID:12857830 doi:http://dx.doi.org/10.1104/pp.102.018481
2. ↑ El-Din El-Assal S, Alonso-Blanco C, Peeters AJ, Wagemaker C, Weller JL, Koornneef M. The role of cryptochrome 2 in flowering in Arabidopsis. Plant Physiol. 2003 Dec;133(4):1504-16. doi: 10.1104/pp.103.029819. Epub 2003 Nov, 6. PMID:14605222 doi:http://dx.doi.org/10.1104/pp.103.029819
3. ↑ Mao J, Zhang YC, Sang Y, Li QH, Yang HQ. From The Cover: A role for Arabidopsis cryptochromes and COP1 in the regulation of stomatal opening. Proc Natl Acad Sci U S A. 2005 Aug 23;102(34):12270-5. Epub 2005 Aug 10. PMID:16093319 doi:http://dx.doi.org/0501011102
4. ↑ Canamero RC, Bakrim N, Bouly JP, Garay A, Dudkin EE, Habricot Y, Ahmad M. Cryptochrome photoreceptors cry1 and cry2 antagonistically regulate primary root elongation in Arabidopsis thaliana. Planta. 2006 Oct;224(5):995-1003. Epub 2006 May 9. PMID:16703358 doi:http://dx.doi.org/10.1007/s00425-006-0280-6
5. ↑ Endo M, Mochizuki N, Suzuki T, Nagatani A. CRYPTOCHROME2 in vascular bundles regulates flowering in Arabidopsis. Plant Cell. 2007 Jan;19(1):84-93. Epub 2007 Jan 26. PMID:17259260 doi:http://dx.doi.org/tpc.106.048157
6. ↑ Tessadori F, Schulkes RK, van Driel R, Fransz P. Light-regulated large-scale reorganization of chromatin during the floral transition in Arabidopsis. Plant J. 2007 Jun;50(5):848-57. Epub 2007 Apr 23. PMID:17470059 doi:http://dx.doi.org/TPJ3093
7. ↑ Millenaar FF, van Zanten M, Cox MC, Pierik R, Voesenek LA, Peeters AJ. Differential petiole growth in Arabidopsis thaliana: photocontrol and hormonal regulation. New Phytol. 2009;184(1):141-52. doi: 10.1111/j.1469-8137.2009.02921.x. Epub 2009 , Jun 24. PMID:19558423 doi:http://dx.doi.org/10.1111/j.1469-8137.2009.02921.x
8. ↑ van Zanten M, Tessadori F, McLoughlin F, Smith R, Millenaar FF, van Driel R, Voesenek LA, Peeters AJ, Fransz P. Photoreceptors CRYTOCHROME2 and phytochrome B control chromatin compaction in Arabidopsis. Plant Physiol. 2010 Dec;154(4):1686-96. doi: 10.1104/pp.110.164616. Epub 2010 Oct, 8. PMID:20935177 doi:http://dx.doi.org/10.1104/pp.110.164616
9. ↑ Nefissi R, Natsui Y, Miyata K, Oda A, Hase Y, Nakagawa M, Ghorbel A, Mizoguchi T. Double loss-of-function mutation in EARLY FLOWERING 3 and CRYPTOCHROME 2 genes delays flowering under continuous light but accelerates it under long days and short days: an important role for Arabidopsis CRY2 to accelerate flowering time in continuous light. J Exp Bot. 2011 May;62(8):2731-44. doi: 10.1093/jxb/erq450. Epub 2011 Feb 4. PMID:21296763 doi:http://dx.doi.org/10.1093/jxb/erq450
10. ↑ Lian HL, He SB, Zhang YC, Zhu DM, Zhang JY, Jia KP, Sun SX, Li L, Yang HQ. Blue-light-dependent interaction of cryptochrome 1 with SPA1 defines a dynamic signaling mechanism. Genes Dev. 2011 May 15;25(10):1023-8. doi: 10.1101/gad.2025111. Epub 2011 Apr 21. PMID:21511872 doi:http://dx.doi.org/10.1101/gad.2025111
11. ↑ Zuo Z, Liu H, Liu B, Liu X, Lin C. Blue light-dependent interaction of CRY2 with SPA1 regulates COP1 activity and floral initiation in Arabidopsis. Curr Biol. 2011 May 24;21(10):841-7. doi: 10.1016/j.cub.2011.03.048. Epub 2011, Apr 21. PMID:21514160 doi:http://dx.doi.org/10.1016/j.cub.2011.03.048
12. ↑ Boccalandro HE, Giordano CV, Ploschuk EL, Piccoli PN, Bottini R, Casal JJ. Phototropins but not cryptochromes mediate the blue light-specific promotion of stomatal conductance, while both enhance photosynthesis and transpiration under full sunlight. Plant Physiol. 2012 Mar;158(3):1475-84. doi: 10.1104/pp.111.187237. Epub 2011 Dec, 6. PMID:22147516 doi:http://dx.doi.org/10.1104/pp.111.187237
13. ↑ Herbel V, Orth C, Wenzel R, Ahmad M, Bittl R, Batschauer A. Lifetimes of Arabidopsis cryptochrome signaling states in vivo. Plant J. 2013 May;74(4):583-92. doi: 10.1111/tpj.12144. Epub 2013 Mar 15. PMID:23398192 doi:http://dx.doi.org/10.1111/tpj.12144
14. ↑ Gould PD, Ugarte N, Domijan M, Costa M, Foreman J, Macgregor D, Rose K, Griffiths J, Millar AJ, Finkenstadt B, Penfield S, Rand DA, Halliday KJ, Hall AJ. Network balance via CRY signalling controls the Arabidopsis circadian clock over ambient temperatures. Mol Syst Biol. 2013;9:650. doi: 10.1038/msb.2013.7. PMID:23511208 doi:http://dx.doi.org/10.1038/msb.2013.7
15. ↑ Jia KP, Luo Q, He SB, Lu XD, Yang HQ. Strigolactone-regulated hypocotyl elongation is dependent on cryptochrome and phytochrome signaling pathways in Arabidopsis. Mol Plant. 2014 Mar;7(3):528-40. doi: 10.1093/mp/sst093. Epub 2013 Oct 14. PMID:24126495 doi:http://dx.doi.org/10.1093/mp/sst093
16. ↑ Liu Y, Li X, Li K, Liu H, Lin C. Multiple bHLH proteins form heterodimers to mediate CRY2-dependent regulation of flowering-time in Arabidopsis. PLoS Genet. 2013;9(10):e1003861. doi: 10.1371/journal.pgen.1003861. Epub 2013 Oct, 10. PMID:24130508 doi:http://dx.doi.org/10.1371/journal.pgen.1003861
17. ↑ Engelhard C, Wang X, Robles D, Moldt J, Essen LO, Batschauer A, Bittl R, Ahmad M. Cellular metabolites enhance the light sensitivity of Arabidopsis cryptochrome through alternate electron transfer pathways. Plant Cell. 2014 Nov;26(11):4519-31. doi: 10.1105/tpc.114.129809. Epub 2014 Nov, 26. PMID:25428980 doi:http://dx.doi.org/10.1105/tpc.114.129809
18. ↑ Xu C, Li Y, Yu Y, Zhang Y, Wei S. Suppression of Arabidopsis flowering by near-null magnetic field is affected by light. Bioelectromagnetics. 2015 Sep;36(6):476-9. doi: 10.1002/bem.21927. Epub 2015 Jun , 11. PMID:26095447 doi:http://dx.doi.org/10.1002/bem.21927
19. ↑ Jourdan N, Martino CF, El-Esawi M, Witczak J, Bouchet PE, d'Harlingue A, Ahmad M. Blue-light dependent ROS formation by Arabidopsis cryptochrome-2 may contribute toward its signaling role. Plant Signal Behav. 2015;10(8):e1042647. doi: 10.1080/15592324.2015.1042647. PMID:26179959 doi:http://dx.doi.org/10.1080/15592324.2015.1042647
20. ↑ Pedmale UV, Huang SC, Zander M, Cole BJ, Hetzel J, Ljung K, Reis PAB, Sridevi P, Nito K, Nery JR, Ecker JR, Chory J. Cryptochromes Interact Directly with PIFs to Control Plant Growth in Limiting Blue Light. Cell. 2016 Jan 14;164(1-2):233-245. doi: 10.1016/j.cell.2015.12.018. Epub 2015, Dec 24. PMID:26724867 doi:http://dx.doi.org/10.1016/j.cell.2015.12.018
21. ↑ Lin C, Yang H, Guo H, Mockler T, Chen J, Cashmore AR. Enhancement of blue-light sensitivity of Arabidopsis seedlings by a blue light receptor cryptochrome 2. Proc Natl Acad Sci U S A. 1998 Mar 3;95(5):2686-90. doi: 10.1073/pnas.95.5.2686. PMID:9482948 doi:http://dx.doi.org/10.1073/pnas.95.5.2686
22. ↑ Ahmad M, Jarillo JA, Smirnova O, Cashmore AR. Cryptochrome blue-light photoreceptors of Arabidopsis implicated in phototropism. Nature. 1998 Apr 16;392(6677):720-3. PMID:9565033 doi:http://dx.doi.org/10.1038/33701
23. ↑ Yu X, Liu H, Klejnot J, Lin C. The Cryptochrome Blue Light Receptors. Arabidopsis Book. 2010 Sep 23;8:e0135. doi: 10.1199/tab.0135. PMID:21841916 doi:http://dx.doi.org/10.1199/tab.0135
24. ↑ Jeong RD, Chandra-Shekara AC, Barman SR, Navarre D, Klessig DF, Kachroo A, Kachroo P. Cryptochrome 2 and phototropin 2 regulate resistance protein-mediated viral defense by negatively regulating an E3 ubiquitin ligase. Proc Natl Acad Sci U S A. 2010 Jul 27;107(30):13538-43. doi:, 10.1073/pnas.1004529107. Epub 2010 Jul 12. PMID:20624951 doi:http://dx.doi.org/10.1073/pnas.1004529107