eprintid: 26412
rev_number: 23
eprint_status: archive
userid: 1395
dir: disk0/00/02/64/12
datestamp: 2019-05-23 06:28:56
lastmod: 2020-05-25 12:28:22
status_changed: 2019-05-23 06:28:56
type: doctoralThesis
metadata_visibility: show
creators_name: Maximowitsch, Egle
title: Molecular mechanisms of spectral tuning and excited-state decay in phytochrome photoreceptors
subjects: ddc-500
divisions: i-140001
adv_faculty: af-14
cterms_swd: phytochrome
cterms_swd: charge transfer
cterms_swd: electron transfer
cterms_swd: spectral tuning
cterms_swd: spectral shift
abstract: Most organisms on earth are able to sense light, to which they adapt their behavior by using photoreceptor proteins containing light-absorbing chromophores. Phytochrome photoreceptors contain a covalently-attached tetrapyrrole chromophore and switch between two thermally stable forms, a red-absorbing (Pr) and a far-red-absorbing (Pfr) state. Although phytochromes have been studied for more than fifty years, the molecular mechanisms defining their photoinduced properties are not fully understood, hampering the efficient engineering of phytochrome-based molecular tools. The computational study presented in this thesis combines quantum chemical calculations and molecular dynamics simulations in order to elucidate the molecular mechanisms of spectral tuning and excited-state decay in phytochromes. The calculations have demonstrated that the spectral red shift of the Pfr state is induced by the hydrogen bond formation between the chromophore and a highly conserved aspartate. Here it is also shown how the formation of this hydrogen bond is coupled to dynamics of other active-site interactions. In addition, the chromophore deprotonation by a protein residue is proposed to contribute to the absorption at the Q-band blue shoulder in the Pr-state spectrum. For the first time, the photoinduced electron transfer coupled to proton transfer was characterized in phytochromes. These charge transfer pathways may contribute to the excited-state decay by quenching fluorescence and influencing photoproduct formation. The discoveries provided in this thesis will facilitate further phytochrome investigations and the rational design of phytochrome-based fluorescent markers and optogenetic tools.
date: 2020
id_scheme: DOI
id_number: 10.11588/heidok.00026412
ppn_swb: 1698672829
own_urn: urn:nbn:de:bsz:16-heidok-264127
date_accepted: 2019-04-01
advisor: HASH(0x558eaa7dd560)
language: eng
bibsort: MAXIMOWITSMOLECULARM2020
full_text_status: public
citation:   Maximowitsch, Egle  (2020) Molecular mechanisms of spectral tuning and excited-state decay in phytochrome photoreceptors.  [Dissertation]     
document_url: https://archiv.ub.uni-heidelberg.de/volltextserver/26412/1/PhDthesis_Egle_Maximowitsch_2019.pdf