Spectroscopic investigation of phytochromes and NIR fluorescent variants
type: CreativeWork
description: In this work, vibrational spectroscopic methods (resonance Raman [RR] and infrared absorption [IR]) were used for the investigation of phytochromes. Phytochromes are bistable photoreceptor proteins that bind bilins (BV, PCB, PΦB) as chromophores. Various plant, cyanobacterial, and bacterial variants regulate biological processes through the light dependent switching between metastable states that absorb red and far-red light (Pr and Pfr). The aim of the work was the elucidation of the mechanisms of photoinduced processes in different phytochromes. In the first part of the work, plant phytochromes were investigated. As in many (cyano-)bacterial variants, the Pr and Pfr states of plant phytochromes are not homogeneous, but instead exist as conformational equilibria of sub-states (I, II). As shown in this work, the distribution between Pfr-I and Pfr-II in plant phytochromes is affected i.a. by the N-terminal extension and binding of PIF proteins (phytochrome interaction factors), which in turn modulates the lifetime of the Pfr state. Furthermore, the photosensor constructs with and without the PHY domain (PAS-GAF-PHY [PGP], PAS-GAF [PG]) were analyzed in solution and in the crystalline state. While the respective Pr states have unaltered chromophore structures, PCB adopts a configuration similar to the Meta-Rc state in the photoproduct of the truncated PG variant. The investigations on cyanobacterial phytochromes in the second part of the work focused on the PCB-binding cyanobacteriochrome (CBCR) Slr-GAF3, which converts to a metastable green-absorbing (Pg) state after photoactivation of Pr. The unusual green absorption properties were analyzed on the basis of four different models proposed for the Pg state. A plausible explanation for the hypsochromic shift of the absorption bands is a twisted configuration of the pyrrole rings A and D in combination with a hydrated chromophore binding pocket. At low temperatures, Slr-GAF3 converts to an orange absorbing (Po) state. V…
abstract: In this work, vibrational spectroscopic methods (resonance Raman [RR] and infrared absorption [IR]) were used for the investigation of phytochromes. Phytochromes are bistable photoreceptor proteins that bind bilins (BV, PCB, PΦB) as chromophores. Various plant, cyanobacterial, and bacterial variants regulate biological processes through the light dependent switching between metastable states that absorb red and far-red light (Pr and Pfr). The aim of the work was the elucidation of the mechanisms of photoinduced processes in different phytochromes. In the first part of the work, plant phytochromes were investigated. As in many (cyano-)bacterial variants, the Pr and Pfr states of plant phytochromes are not homogeneous, but instead exist as conformational equilibria of sub-states (I, II). As shown in this work, the distribution between Pfr-I and Pfr-II in plant phytochromes is affected i.a. by the N-terminal extension and binding of PIF proteins (phytochrome interaction factors), which in turn modulates the lifetime of the Pfr state. Furthermore, the photosensor constructs with and without the PHY domain (PAS-GAF-PHY [PGP], PAS-GAF [PG]) were analyzed in solution and in the crystalline state. While the respective Pr states have unaltered chromophore structures, PCB adopts a configuration similar to the Meta-Rc state in the photoproduct of the truncated PG variant. The investigations on cyanobacterial phytochromes in the second part of the work focused on the PCB-binding cyanobacteriochrome (CBCR) Slr-GAF3, which converts to a metastable green-absorbing (Pg) state after photoactivation of Pr. The unusual green absorption properties were analyzed on the basis of four different models proposed for the Pg state. A plausible explanation for the hypsochromic shift of the absorption bands is a twisted configuration of the pyrrole rings A and D in combination with a hydrated chromophore binding pocket. At low temperatures, Slr-GAF3 converts to an orange absorbing (Po) state. V…
author: Buhrke, David
language: en
license: http://rightsstatements.org/vocab/InC/1.0/
date published: 2019
date modified: 2026-07-27T21:28:35Z
provider: Technische Universität Berlin
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Technische Universität Berlin

PropertyValue
property ID: DOI
value: 10.14279/depositonce-8309