The Photosynthetic Reaction Centre from the Purple Bacterium Rhodopseudomonasviridis

The development and applications of multidimensional biomolecular spectroscopy illustrated by photosynthetic light harvesting

The parallel and synergistic developments of atomic resolution structural information, new spectroscopic methods, their underpinning formalism, and the application of sophisticated theoretical methods have led to a step function change in our understanding of photosynthetic light harvesting, the process by which photosynthetic organisms collect solar energy and supply it to their reaction centers to initiate the chemistry of photosynthesis. The new spectroscopic methods, in particular multidimensional spectroscopies, have enabled a transition from recording rates of processes to focusing on mechanism. We discuss two ultrafast spectroscopies - two-dimensional electronic spectroscopy and two-dimensional electronic-vibrational spectroscopy - and illustrate their development through the lens of photosynthetic light harvesting. Both spectroscopies provide enhanced spectral resolution and, in different ways, reveal pathways of energy flow and coherent oscillations which relate to the quantum mechanical mixing of, for example, electronic excitations (excitons) and nuclear motions. The new types of information present in these spectra provoked the application of sophisticated quantum dynamical theories to describe the temporal evolution of the spectra and provide new questions for experimental investigation. While multidimensional spectroscopies have applications in many other areas of science, we feel that the investigation of photosynthetic light harvesting has had the largest influence on the development of spectroscopic and theoretical methods for the study of quantum dynamics in biology, hence the focus of this review. We conclude with key questions for the next decade of this review.

Control of Photoinduced Electron Transfer Using Complex Formation of Water-Soluble Porphyrin and Polyvinylpyrrolidone

Inspired by the natural photosynthetic system in which proteins control the electron transfer from electron donors to acceptors, in this research, artificial polymers were tried to achieve this control effect. Polyvinylpyrrolidone (PVP) was found to form complex with pigments 5,10,15,20-tetrakis-(4-sulfonatophenyl) porphyrin (TPPS) and its zinc complex (ZnTPPS) quantitatively through different interactions (hydrogen bonds and coordination bonds, respectively). These complex formations hinder the interaction between ground-state TPPS or ZnTPPS and an electron acceptor (methyl viologen, MV2+) and could control the photoinduced electron transfer from TPPS or ZnTPPS to MV2+, giving more electron transfer products methyl viologen cationic radical (MV+•). Other polymers such as PEG did not show similar results, indicating that PVP plays an important role in controlling the photoinduced electron transfer.

Genome Sequence of the Alphaproteobacterium Blastochloris sulfoviridis DSM 729, Which Requires Reduced Sulfur as a Growth Supplement and Contains Bacteriochlorophyll b

The genome sequence of Blastochloris sulfoviridis is 3.85 Mb with a GC content of 68%. Its nearest relative is B. tepida (average nucleotide identity [ANI], 91.5%), followed by B. viridis (ANI, 83%). According to ANI and whole-genome-based phylogenetic analysis, the nearest relatives of Blastochloris are Rhodoplanes and Rhodopseudomonas, confirming the recognition of distinct genera.

A brief survey of the "cytochromome"

Multihaem cytochromes c are widespread in nature where they perform numerous roles in diverse anaerobic metabolic pathways. This is achieved in two ways: multihaem cytochromes c display a remarkable diversity of ways to organize multiple hemes within the protein frame; and the hemes possess an intrinsic reactive versatility derived from diverse spin, redox and coordination states. Here we provide a brief survey of multihaem cytochromes c that have been characterized in the context of their metabolic role. The contribution of multihaem cytochromes c to dissimilatory pathways handling metallic minerals, nitrogen compounds, sulfur compounds, organic compounds and phototrophism are described. This aims to set the stage for the further exploration of the vast unknown "cytochromome" that can be anticipated from genomic databases.

Multivariate curve resolution of rapid-scan FTIR difference spectra of quinone photoreduction in bacterial photosynthetic membranes

Photosynthetic reaction centres and membranes are systems of particular interest and are often taken as models to investigate the molecular mechanisms of selected bioenergetic reactions. In this work, a multivariate curve resolution by alternating least squares procedure is detailed for resolution of time-resolved difference FTIR spectra probing the evolution of quinone reduction in photosynthetic membranes from Rhodobacter sphaeroides under photoexcitation. For this purpose, different data sets were acquired in the same time range and spectroscopic domain under slightly different experimental conditions. To enable resolution and provide meaningful results the different data sets were arranged in an augmented matrix. This strategy enabled recovery of three different species despite rank-deficiency conditions. It also results in better definition (identity and evolution) of the contributions. From the resolved spectra, the species have been attributed to: 1. the formation of ubiquinol, more precisely the disappearance of Q/appearance of QH(2); 2. conformational change of the protein in the surrounding biological medium; 3. oxidation of diaminodurene, a redox mediator. Because, moreover, results obtained from augmented data sets strategies enable quantitative and qualitative interpretation of concentration profiles, other effects, for example the consequence of repeated light excitation of the same sample, choice of illumination power, or the number of spectra accumulated could be compared and discussed.

Visions for novel biophysical elucidations of extracellular matrix networks

The extracellular matrix consists of multifunctional molecules, which are composed of a large numbers of different domains. Clearly these domains and even the entire molecules do not function independently as isolated species, but interact with each other in large networks. In many cases specific regions of the networks may be considered as molecular machines in which the different molecules are arranged in highly defined spatial structures and act in a dynamic, concerted fashion. At present most structural information is limited to single molecules, and dynamics have been measured mainly for pairs of interacting partners in solution. Work needs to be extended to large integrated systems and the functions of molecular machines need to be explored. Electron tomography, fluorescence resonance energy transfer, and other biophysical techniques are very promising.