Effect of chromophore exchange on the resonance Raman spectra of recombinant phytochromes

• DOI: 10.1016/s0014-5793(97)00969-1
• Publication Date: 2002-07-25T16:08:36Z
• Authors: C Kneip; D Mozley; P Hildebrandt; W Gärtner; S.E Braslavsky; K Schaffner
• Keywords: Phycocyanobilin; Chromophore; Phytochrome; Phytochrome A; Tetrapyrrole; Resonance Raman spectroscopy

The recombinant 65‐kDa polypeptide of phyA oat phytochrome was expressed by yeast Pichia pastoris and assembled into two chromopeptides with the chromophores phytochromobilin (PΦB) phycocyanobilin (PCB), respectively. P r fr states protein variants were characterized resonance Raman (RR) spectroscopy compared native demonstrating that deletion C‐terminal half does not alter structure chromophore site within N‐terminal half. Most RR spectral changes observed upon replacing PΦB PCB can be attributed exclusively to altered vibrational mode compositions due different ring D substitutions (vinyl vs. ethyl), implying structures are largely same for PΦB‐ PCB‐assembled phytochromes. Only in state may also reflect subtle differences conformations , presumably brought about specific steric requirements vinyl ethyl groups.