The structure and thermal motion of B800-850 LH2 complex fromRps. Acidophilaat 2.0  Å: functionally relevant motion

Abstract

Spagna & Camalli (J. Appl. Cryst. (1999) 32, 934-942) presented an analysis of weighting schemes currently used by crystallographers to refine small or medium sized crystal structures by least squares method. These schemes are empirical functions to calculate the weights based on the observed quantities or on the standard uncertainty of the observations, derived by counting statistics. The first recommendation in the paper of Schwarzenbach et al. (Acta Cryst. (1989) A45, 63-75) states 'All reflections to be used in the refinement process should be measured more than once...', according the theory of least squares where the weights should be the inverse of the variance-covariance matrix of the observations. To follow this recommendation, we have chosen a solved structure and using the same crystal well stable under X-rays, we carried out a data collection where each reflection was measured six times. 31157 reflections (resolution 0.80 Å) were collected and processed to yield 4820 unique reflections (merging R factor = 0.015). 4121 observed (I > 3σ(I)) reflections were used in subsequent calculations. The structure was refined using various strategies and the results are compared against the standard experiment.

Bacterial Light-Harvesting Complexes Showing Giant Second-Order Nonlinear Optical Response as Revealed by Hyper-Rayleigh Light Scattering

“…tepidum LH2 either. (4) Previous works 20,21 have argued that the BChlto-Car stoichiometric ratio in LH2 is 2:1, that is, a second group of Car's exists. However, the existing crystal structures cannot conclusively identify the second group, 20−22 and the issue remains ambiguous.…”

Protein Structural Deformation Induced Lifetime Shortening of Photosynthetic Bacteria Light-Harvesting Complex LH2 Excited State

“…The recent x-ray crystal structure of LH2 from Rps. acidophila of better resolution (2 Å ) shows that nine segments of C-terminus residues point outward on the periplasmic side (Papiz et al, 2003), which provides a good chance for the LH2 complex forming the chemical binding between the terminal carboxylic groups and surface titanium atoms on the nanoparticles, though the cavity was filled with detergent molecules or unremoved lipid molecules as shown by the neutron scattering experiment (Prince et al, 2003). Therefore, the strategy of assembling of LH2 onto the TiO 2 nanoparticle by means of the C-terminal carboxylic anchoring group can be successful as shown schematically in Fig.…”

“…Several groups have succeeded in the immobilization of the photosynthetic bacteria light-harvesting LH2 complex on mica and glass surface to investigate the single molecular fluorescence of LH2 (Bopp et al, 1997(Bopp et al, , 1999Tietz et al, 1999;Rutkauskas et al, 2004). The crystal structure of the LH2 complex of the purple bacterium Rhodopseudomonas acidophila shows that the LH2 molecule exhibits a high symmetry with a ninefold rotational axis defined by nine abdipeptides (McDermott et al, 1995;Papiz et al, 2003). The basic building block is the protein ab-heteromer that binds three BChl a molecules and two carotenoid (Car) molecules (Papiz et al, 2003).…”

“…The crystal structure of the LH2 complex of the purple bacterium Rhodopseudomonas acidophila shows that the LH2 molecule exhibits a high symmetry with a ninefold rotational axis defined by nine abdipeptides (McDermott et al, 1995;Papiz et al, 2003). The basic building block is the protein ab-heteromer that binds three BChl a molecules and two carotenoid (Car) molecules (Papiz et al, 2003). The total 27 BChl a molecules form two concentric rings supported by the ab-dipeptides.…”

Spectral Trends in the Fluorescence of Single Bacterial Light-Harvesting Complexes: Experiments and Modified Redfield Simulations

“…acidophila and Rhodospirillum (Rs.) molischianum (2)(3)(4) show that both complexes consist of two rings of bacteriochlorophyll (BChl) a molecules in a protein scaffold and that these are responsible for the absorption bands around 800 and 850 nm, referred to as B800 and B850, respectively. Cryoelectron microscopy has shown that the structure of LH2 of Rhodobacter (Rb.)…”