Authors: Ovidiu Rücker Anne Köhler Beate Behammer Katja Sichau Jörg Overmann
Publish Date: 2011/07/31
Volume: 194, Issue: 2, Pages: 123-134
Abstract
Whole cells of the purple sulfur bacterium strain 970 exhibit an unusual absorption peak at 963 nm Its closest relatives Thiorhodovibrio Trv winogradskyi DSM6702T and strain 06511 display a bacteriochlorophyll BChl a absorption peak at 867 nm that is characteristic for most lightharvesting complexes 1 LHC1 of proteobacteria The puf operons encoding the LHC1 and reaction center proteins were amplified cloned and sequenced and for the Trv winogradskyi strains show the common pufBALMC gene arrangement whereas strain 970 contains a second pufBA copy downstream of pufC Only pufB 1 A 1 is transcribed and the corresponding mRNA fragment had an increased stability Alignments of the deduced protein sequences showed that the LHC1 polypeptides are closely related to those of Thermochromatium Tch tepidum A deletion between αHis0 and αTrp+11 thought to be responsible for the redshifted Q y absorption in Tch tepidum was also detected in strain 970 and Trv winogradskyi whereas αLys+12 is replaced by histidine only in strain 970 Based on our structural modeling the side chain of this αHis is predicted to be in close proximity to the BChl a suggesting that it exerts a modulating effect on the spectral properties of the highly unusual LHC1 complex of strain 970
Keywords: