Electron transfer dynamics of Rhodopseudomonas viridis reaction centers with a modified binding site for the accessory bacteriochlorophyll.

Femtosecond spectroscopy in combination with site-directed mutagenesis was used to study the influence of histidine L153 in primary electron transfer in the reaction center of Rhodopseudomonas viridis. Histidine was replaced by cysteine, glutamate, or leucine. The exchange to cysteine did not lead to significant changes in the primary reaction dynamics.

Electron transfer from the tetraheme cytochrome to the special pair in the Rhodopseudomonas viridis reaction center: effect of mutations of tyrosine L162.

The structure of the photosynthetic reaction center (RC) from Rhodopseudomonas viridis is known to high resolution. It contains a firmly bound tetraheme cytochrome from which electrons are donated to a special pair (P) of bacteriochlorophylls, which is photooxidized upon absorption of light. Tyrosine at position 162 of the L-subunit of the reaction center (L 162 Y) is a highly conserved residue positioned halfway between P and the proximal heme group (c-559) of the cytochrome.

A system for site-specific mutagenesis of the photosynthetic reaction center in Rhodopseudomonas viridis.

The purple non-sulfur bacterium Rhodopseudomonas viridis contains a photosynthetic reaction center which has been structurally resolved to 2.3 A providing a unique basis for the study of biological electron transfer processes by the method of site-specific mutagenesis. Here we report the construction of a puf operon deleted mutant strain incapable of photosynthetic growth.