John Postgate

Biography

 John Raymond Postgate was born on 24 June 1922,[2][12] as the elder son of the writer Raymond Postgate and Daisy Postgate, née Lansbury, private secretary to her father George Lansbury, the politician who was Labour Party Leader of the Opposition 1932-35. He had one brother, Oliver Postgate, later a well-known animator and producer for British television. Several other members of the Postgate family were notable in a variety of fields. His cousin is the actress Angela Lansbury. He attended kindergarten and primary private schools in Golders Green, North London, before moving at age 11 to Kingsbury County School; he was evacuated to Devon at the start of World War II. In 1941 he was awarded an exhibition scholarship to Balliol College, Oxford, where he achieved a first class degree in Chemistry. He had also taken a special biochemistry course. His final examination involved research on the adaptation of bacteria to unfavourable environments and, supported by a grant from the Medical Research Council plus a Studentship from Balliol (which the MRC deducted from his grant), he spent a year reading Microbial Chemistry before doing research for a doctorate on aspects of how bacteria adapt to resist sulphonamide drugs.[13] Sulfomamide drugs had been shown by D D Woods, his supervisor, to block the enzyme assimilating the metabolite p-aminobenzoic acid (PABA for short), a precursor of folic acid, by blocking the enzyme's active site. A substantial excess of a sulfonamide needed to put a complete stop to PABA assimilation.[14] Postgate's research was to study sulfonamide action on a species of bacteria that required PABA from the environment as a vitamin; it gave him valuable experience of competition in enzymology.

Research Interest

 Career and research In 1948 Postgate obtained a Research Fellowship at the Chemical Research Laboratory (CRL) in Teddington, West London, to investigate the biochemistry of the sulphate-reducing bacteria. A small microbiology group, led by K R Butlin,[15] was researching their role in iron corrosion and other civil and industrial nuisances. The group also investigated and advised on diverse problems in economic microbiology which had been brought to the laboratory. The bacteria were known to be strict anaerobes which live by converting mineral sulphates to hydrogen sulphide. They are difficult to culture and to separate from other soil bacteria in the laboratory, but Butlin's group had isolated a few pure strains. Postgate managed to culture large populations of the organism and his experience of competition informed his first paper, in which he showed that selenates are powerful competitive inhibitors of sulphate reduction.[16] He went on to obtain biochemical evidence on how they consume sulphates and carbon sources,[17][18] but his most influential finding was cytochrome C3.,[19][20] a discovery that has been described as "seminal".[10] Cytochromes are iron-containing proteins found in the cells of all air-breathing creatures from bacteria and plants to humans; they were known to be part of the aerobic respiratory apparatus and were widely understood to be absent from anaerobes. The appearance of a cytochrome, one which had an unusually large amount of iron, in a strict anaerobe conflicted with current theory. However soon it became accepted and the concept emerged of "anaerobic respiration", based on reducing nitrate, carbonate or similar oxygen-containing minerals. Postgate's research formed the basis of worldwide research on these bacteria and their cytochromes, as well as the discovery of many new genera; sulphate reducers are now known to constitute a diverse biosphere of their own.[21] Postgate also enjoyed the Group's more practical problems. His laboratory strain reduced sulphates at hitherto unheard-of rates, and their speed revived a wartime possibility of using them to manufacture sulphur for industry by fermenting waste with sulphate. This would mimic the way in which most of the world's native sulphur was deposited over geological time. A post-war World sulphur shortage was damaging post-war British industry, so he and Butlin were sent to Cyrenaica to sample a sulphur spring and check specimens for even better performance.[22] The trip caught the attention of the press, and the microbiological production of sulphur became Butlin's pet project, with Postgate advising. Postgate enjoyed the practical side and also made advances in understanding the biochemistry of the bacteria. The group expanded and widened its remit to encompass the microbiological production of sulphur and the treatment of chemical effluents; it also took over the National Collection of Industrial Bacteria. He was absorbed into its staff in 1950 as Senior Scientific Officer and promoted Principal Scientific Officer in 1952.[23] The group expanded and widened its remit to encompass the microbiological production of sulphur and the treatment of chemical effluents; it also took over the National Collection of Industrial Bacteria. In 1959, for controversial reasons, Butlin's group was disbanded and its staff and collection redeployed. Postgate was released to take a post at the Microbiological Research Establishment (MRE), part of the Porton Down research complex at Porton near Salisbury in Wiltshire, to undertake fundamental research on how bacteria survive mild stresses such as near starvation, using both continuous and synchronous culture of bacteria. His extensive paper on the survival of starvation by klebsiella bacteria reopened a research topic largely dormant since the 1920s and introduced the concept of cryptic growth (a sort of necrophagy) in the persistence of bacterial populations in ancient isolated environments such as salt inclusions or fossils.[24] He was promoted Senior Principal Scientific Officer in 1961. In 1962 he was given leave to take up a Visiting Professorship of Microbiology at the University of Illinois, in the United States, to finish off some earlier research on sulphate-reducing bacteria and undertake some teaching duties. He returned to MRE in early 1963.[20] A change of emphasis in the research remit of MRE led to his resignation and in 1963 he was Appointed Assistant Director of the Agricultural Research Council's newly formed multidisciplinary Unit of Nitrogen Fixation (UNF), with the chemist Professor Joseph Chatt FRS as Director. Postgate's job was to plan and direct its biological research programme.[25] The Unit settled at the University of Sussex in late 1964, and in 1965 the University appointed Postgate Professor of Microbiology in addition to his UNF position, with only postgraduate teaching duties. The Unit's biological research was restricted to free-living nitrogen fixers, chosen as more amenable material for its research than those requiring a plant symbiosis. Its approach ranged from biochemical enzymology to microbial physiology and general microbiology, and in due course it introduced the genetics, and was genuinely collaborative, with everyone, including Postgate, working at the bench. Almost all its research publications were multi-authored and Postgate's name appeared only on those original papers to which he had actively contributed - though he prescribed and oversaw all his staff's research directions. Outstanding papers were: a series deducing mode of action of nitrogenase, the enzyme responsible for the initial attack of nitrogen, which is an oxygen-sensitive complex of two proteins, iron and molybdenum, which requires energy in the form of Adenosine triphosphate (ATP) to function and which releases hydrogen from water while fixing nitrogen;[26] the elucidation of oxygen-screening processes in an oxygen-tolerant species of nitrogen fixer and the discovery in that microbe of a second nitrogenase containing vanadium in place of molybdenum alongside the regular one;[27] the elucidation of a cluster of some 21 genes which code for the whole nitrogen-fixing system, the creation of mobile genetic elements carrying that cluster and the transfer therewith of the ability to fix nitrogen to wholly new bacteria by genetic manipulation.[28][29] One of the Unit's plasmids came into worldwide use to study the genetics of nitrogen fixation. The Unit's reputation prospered as a world centre for basic research on the subject.[30] Postgate had spent March 1977-March 1978 as Visiting Professor of Microbiology at Oregon State University, U.S.A.. He became Director of the UNF when Chatt retired in 1980 and in turn Postgate retired in 1987. The UNF was later absorbed by the John Innes Centre at Norwich.