Guest Editorial

This Special Issue of Photochemical & Photobiological Sciences assembles a series of papers dedicated to Jim Barber on the occasion of his 65th birthday in July 2005. In the Introduction to this volume, Bertil Andersson gives an excellent summary of Jim's more recent outstanding contributions to science and succinctly illustrates his persona, that of boundless enthusiasm and drive for most, if not all, things photobiological. However, it is appropriate that we should seek to illuminate his career from the very beginning.

Jim was born on July 16th, 1940, and grew up in Portsmouth, a naval town on the south coast of England. He left Grammar School at the age of 16 to take up an engineering apprenticeship at the Signals Research and Development Establishment of the Ministry of Defence located close to the sea-side town of Bournemouth. Here he trained in basic engineering skills, which included day release and evening classes at the local technical college. It was this opportunity, to study for engineering qualifications, which led to an award of a Technical State Scholarship allowing him to enter full time university education.

In 1961 he began the chemical engineering degree course at University College Swansea and a year later converted to pure chemistry. After obtaining a BSc degree in 1963, he was able to realise an ambition to study biology. This was made possible with the help of the Nuffield Foundation, which awarded him a special scholarship to convert from the physical to the biological sciences. With this support he transferred to the University of East Anglia in Norwich, studying initially for a Masters degree in biophysics, followed by a two-year research program leading to a PhD degree. His PhD supervisor at UEA was Professor Jack Dainty, who had trained as a nuclear physicist and who had also converted to the biological sciences. It was Jack Dainty who encouraged Jim to focus his research on the primary processes of photosynthesis and his PhD resulted in a number of papers which explored the interaction between photosynthesis and the active transport of ions, particularly K⁺, Na⁺ and Cl⁻, in the green alga, Chlorella pyrenoidosa. This was the beginning of 40 years of active research into photosynthesis.

In order to broaden his research experience, and aided by the award of the Unilever European Fellowship of the Biochemical Society, he took up a position in the Biophysics Department of the State University of Leiden under the guidance of Professor L.N.M. Duysens. In Professor Duysens's laboratory Jim rubbed shoulders with a number of outstanding scientists, including Professors Jan Amez and Robert Knox, who provided him with considerable encouragement. His training with Jack Dainty in membrane biology was particularly useful when he discovered, during his post-doctoral year, the phenomenon of salt-induced delayed light emission from chloroplasts. He showed that this phenomenon was directly dependent on the size of the membrane potential created by the concentration gradient of different ionic species.

In 1968, after completing this year in Leiden, Jim returned to the UK to become a Lecturer in the Botany Department at Imperial College London. At that time Professor C.P. Whittingham was Head of Department and David A. Walker FRS was the Reader in enzymology. With their help, Jim soon established his own laboratory with research grants and PhD students, focusing much of his attention on the interplay between ionic gradients and their effects on delayed and prompt fluorescence from chloroplasts. It was this focus which gave rise to his detailed analyses of these phenomena in terms of both transmembrane and surface electrical properties and how these properties play a role in energy conversion and the organisation of the photosynthetic apparatus.

In 1974, Jim was promoted to Reader in Plant Physiology and five years later to Professor of Plant Physiology. By this time he had established a large research group with long-term funding from the Agriculture and Food Research Council (AFRC), initially maintaining a focus on the physical properties of thylakoid membranes in relation to the regulation of photosynthesis. By the mid-1980s, Jim changed the main thrust of his research to elucidate the properties of photosystem II (PSII) and engaged in studies ranging from detailed analyses of the isolated D1/D2/cytochrome b-559 reaction centre complex to site-directed mutagenesis of PSII proteins. This redirection was encouraged by the AFRC, and particularly by Professor Harold Woolhouse, Director of the John Innes Institute, Norwich. It became clear that PSII was a weak link in plant metabolism as well as being a major site for herbicide interaction. On the other hand, it was the water-splitting reaction of PSII which fascinated Jim and to which ultimately he was able to contribute in a significant way.

It became obvious during the early 1990s that to fully explain PSII function in molecular terms, particularly the water-splitting reaction, it would be necessary to ascertain its structure. By 1995 Jim's group had devised biochemical methods to isolate PSII from higher plants in a suitable form for structural studies. Using electron microscopy and single-particle image averaging, low-resolution images of PSII were obtained that clearly showed its dimeric organisation, both when it was isolated as a core complex, and as a supercomplex binding its outer light-harvesting system. These biochemical preparations were rigorously analysed for their composition and some of them were used to grow 2D arrays for electron crystallography, yielding structural information at 8–9 Å resolution. Consequently the organisation of the various subunits and their transmembrane helices were revealed for the first time. The next leap forward for Jim's laboratory came from using PSII preparations isolated from cyanobacteria, which yielded 3D crystals suitable for analysis by X-ray crystallography. The resulting structural model was refined to 3.5 Å and provided full information about the protein environments of the various cofactors which underlie PSII function and in particular those involved in the water-splitting process. When the paper was published in Science in 2004, we both knew that Jim had achieved a dream which stemmed back over ten years.

Another exciting element of his most recent studies was the discovery and characterisation of light-harvesting systems that use, as a basic building block, CP43-like proteins. Initially, one of these proteins, the cyanobacterial IsiA protein, was observed to form a ring around the trimeric PSI complex, and further similar structures were found in Prochlorococcus and Acaryochloris, where the CP43-like light-harvesting proteins are encoded by pcb genes. Moreover, his most recent work has shown that some Pcb proteins are also directed to PSII where they also act as a light-harvesting system.

Jim will be the first to acknowledge that without the help and support of his wife Lyn and his many colleagues and students he would not have achieved the level of success he enjoys today, either in the form of his research contributions or the honours that he has received, including election as a Fellow of The Royal Society earlier this year. Likewise, those of us who have worked in Jim's lab count themselves extremely fortunate to have worked in such an active and happy environment.

It is indeed a testament to Jim's enthusiasm and encouragement that so many of his former colleagues have continued to work on various aspects of photosynthesis, some of which are presented in this volume, and it has been a pleasure for us to edit such a wonderful array of original work and detailed perspectives. Jim continues to be an inspirational colleague for so many scientists across a wide variety of fields and we wish him the best for his 65th birthday year and continued success for the future.

Jon Nield and Peter Nixon

Photochemical & Photobiological Sciences Guest Associate Editors

Imperial College, London, UK, October 2005

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