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Views | Duration | ||
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41. Choosing to work on chromatin | 72 | 03:47 | |
42. The importance of histones to chromatin structure | 109 | 04:58 | |
43. The solenoid model | 121 | 05:44 | |
44. Crystallising the nucleosome | 112 | 04:13 | |
45. Electron microscope work and crystallising the histone octamer | 80 | 04:16 | |
46. The high-resolution structure of the nucleosome | 334 | 06:20 | |
47. The solenoid structure and developing new technologies | 1 | 67 | 06:29 |
48. Continuing debate on chromatin | 84 | 03:55 | |
49. Experiments with lead enzyme | 56 | 04:53 | |
50. Work on hammerhead ribozymes with Bill Scott | 171 | 04:52 |
There's still models of the solenoid and there's still a controversy about whether it folds up into... a man called Woodcock... if you don't have H1, you get a zigzag fibre because the H1... And... And even at low salt you can get a zigzag fibre as well. So in the... sorry, at low salt, in the... in the presence of H1, you get a fibre which is zigzag; the nucleosomes and then there's another nucleosome and they zigzag like this. So he said, 'That must be a part of the nucleosome, of nucleosome five 300 angstroms', so he made a model called the zigzag fibre. And it doesn't explain the X-ray diffraction, and later, John... John William, who came in 1985, he published a paper on chromatin from chicken erythrocyte, which is a very stable chromatin and tried to fit the nucleosome into the fibre and we got a reasonable fit. But the... the conflict still continues to this day where people have produced new models. And in fact, just in last week's Nature, Tim Richmond has produced a new model of the chromatin fibre. It doesn't include H1, and so it's totally irrelevant, but he's built up such a head of steam that they have their news and views about it, so I guess I'm going to have to come out of retirement, so to speak, and I'll just field and go in again. H1 is absolutely vital, what he's done is to, this is highly technical, it's very current, so what you have to do is to work hard, you have to go working hard after your Nobel Prize. Because, Roger Kornberg said to me in great surprise when he came, he was sort of naive because he worked in straightforward biochemistry. He says, 'You not only have to discover the methods and the structures but you have to police them.' And you have to police them, because, you know, I... Shakespeare had it all... it was an unweeded garden that grows to seed, things rank and gross and nature possess it merely. And I'm afraid these things, it's like... it's like having weeds coming up and you have to knock off the heads of the thistles... you know, things like that. So... so, the... well, there's no doubt about the 300 angstrom fibre, it has to have H1. And so, what Tim Richmond did was to take his crystal structure, he was trying to work on what's called the chromatozome, that's the... but he never succeeded in crystallising it with the H1. So he's now... he built a model of the 300 angstrom fibre in which he took the crystal structure, his crystal structure, high resolution and he put in cross links assuming that the packing in crystal would reflect the packing in chromatin fibre without H1. That was... that was published in... that was published in Science a couple of years ago and then this last week, in Nature, he published a paper in Nature in which he crystallised a tetra nucleosome but without H1 again. And through various somersaults and tercifications, you know, that is the base changes and so like that, he managed to say, this is consistent with his model. It's quite wrong, in my view, and I'm thinking of writing coming out of retirement, as I said, in this field and writing a note about it... pointing out about H1. So there you are, the subject never ends; well, it does end, but I think we're still policing the field.
Born in Lithuania, Aaron Klug (1926-2018) was a British chemist and biophysicist. He was awarded the Nobel Prize in Chemistry in 1982 for developments in electron microscopy and his work on complexes of nucleic acids and proteins. He studied crystallography at the University of Cape Town before moving to England, completing his doctorate in 1953 at Trinity College, Cambridge. In 1981, he was awarded the Louisa Gross Horwitz Prize from Columbia University. His long and influential career led to a knighthood in 1988. He was also elected President of the Royal Society, and served there from 1995-2000.
Title: Continuing debate on chromatin
Listeners: John Finch Ken Holmes
John Finch is a retired member of staff of the Medical Research Council Laboratory of Molecular Biology in Cambridge, UK. He began research as a PhD student of Rosalind Franklin's at Birkbeck College, London in 1955 studying the structure of small viruses by x-ray diffraction. He came to Cambridge as part of Aaron Klug's team in 1962 and has continued with the structural study of viruses and other nucleoproteins such as chromatin, using both x-rays and electron microscopy.
Kenneth Holmes was born in London in 1934 and attended schools in Chiswick. He obtained his BA at St Johns College, Cambridge. He obtained his PhD at Birkbeck College, London working on the structure of tobacco mosaic virus with Rosalind Franklin and Aaron Klug. After a post-doc at Childrens' Hospital, Boston, where he started to work on muscle structure, he joined to the newly opened Laboratory of Molecular Biology in Cambridge where he stayed for six years. He worked with Aaron Klug on virus structure and with Hugh Huxley on muscle. He then moved to Heidelberg to open the Department of Biophysics at the Max Planck Institute for Medical Research where he remained as director until his retirement. During this time he completed the structure of tobacco mosaic virus and solved the structures of a number of protein molecules including the structure of the muscle protein actin and the actin filament. Recently he has worked on the molecular mechanism of muscle contraction. He also initiated the use of synchrotron radiation as a source for X-ray diffraction and founded the EMBL outstation at DESY Hamburg. He was elected to the Royal Society in 1981 and is a member of a number of scientific academies.
Tags: Nature, John William, Roger Kornberg, William Shakespeare, Tim Richmond
Duration: 3 minutes, 55 seconds
Date story recorded: July 2005
Date story went live: 24 January 2008