The light, oxygen, voltage (LOV) domain proteins are blue light photoreceptors that utilize a noncovalently bound flavin mononucleotide (FMN) cofactor as the chromophore. The modular nature of these proteins has led to their wide adoption in the emerging fields of optogenetics and optobiology, where the LOV domain has been fused to a variety of output domains leading to novel light-controlled applications. In this work, we extend our studies of the subpicosecond to several hundred microsecond transient infrared spectroscopy of the isolated LOV domain AsLOV2 to three full-length photoreceptors in which the LOV domain is fused to an output domain: the LOV-STAS protein, YtvA, the LOV-HTH transcription factor, EL222, and the LOV-histidine kinase, LovK. Despite differences in tertiary structure, the overall pathway leading to cysteine adduct formation from the FMN triplet state is highly conserved, although there are slight variations in rate. However, significant differences are observed in the vibrational spectra and kinetics after adduct formation, which are directly linked to the specific output function of the LOV domain. While the rate of adduct formation varies by only 3.6-fold among the proteins, the subsequent large-scale structural changes in the full-length LOV photoreceptors occur over the micro- to submillisecond time scales and vary by orders of magnitude depending on the different output function of each LOV domain.
Bibliographical noteFunding Information:
*E-mail: firstname.lastname@example.org. ORCID James N. Iuliano: 0000-0003-1213-3292 Agnieszka A. Gil: 0000-0001-7583-3080 Sergey P. Laptenok: 0000-0002-6468-3010 Andras Lukacs: 0000-0001-8841-9823 Markus Fischer: 0000-0001-7243-4199 Jarrod B. French: 0000-0002-6762-1309 Stephen R. Meech: 0000-0001-5561-2782 Peter J. Tonge: 0000-0003-1606-3471 Present Address @S.P.L.: Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, P.O. Box 4700, Thuwal 23955-6900, Kingdom of Saudi Arabia. Funding This study was supported by the EPSRC (EP/G002916 to S.R.M.) and the National Science Foundation (NSF) (CHE-1223819 to P.J.T.). J.N.I. was supported by a National Institutes of Health Chemistry-Biology Interface training grant (T32GM092714). A.L. is a Bolyai Jańos Research Fellow and was supported by OTKA NN113090. J.A. was supported by the NSF REU program at Stony Brook University (NSF-CHE-1358959). S.A.H.A. was a Fulbright Scholar and gratefully acknowledges support from the Fulbright Program. J.T.C. was supported by the IMSD-MERGE Program at Stony Brook University (5R25GM103962-04). Notes The authors declare no competing financial interest.
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