News 2005
August 2005
Daresbury Scientists Reveal Enzyme Mechanism
Understanding enzyme catalysis in the Nitrogen Cycle - crystallography at atomic
resolution on MAD 10.1 at the SRS
The
nitrogen cycle is a process comparable to photosynthes is in biological significance.
Copper containing nitrite reductases are enzymes that perform a crucial catalytic
step in this cycle - the conversion on nitrite (NO 2 -) to nitric oxide (NO).
This reaction removes nitrogen from the soil and has agronomic, environmental
and medical impacts. We used 'crystal harvesting' and substrate-soaking techniques
to obtain crystal structures at atomic resolution (0.9, 1.15 and 1.12 Å)
of Achromobacter cycloclastes nitrite reductase in its resting state, nitrite-bound
and NO-bound forms. In addition, a structure at 1.1 Å resolution revealed
the presence of both nitrite and NO at the catalytic type 2 copper centres.
The structure of the resting enzyme, measured on the MAD 10.1 beamline, is the
highest resolution reported for any copper protein. These structures have provided
insights into the process of nitrite reduction, from the initial binding of
substrate to the type 2 copper atom, its repositioning prior to catalysis, bond
breakage (O-NO) and the formation of a stable NO adduct.
This work reports a collaboration between the Molecular Biophysics Group at Daresbury and the John Innes Centre, Norwich, and is published in the latest volume of the Proceedings of the National Academy of Sciences (USA) : Svetlana Antonyuk, Richard W. Strange, Gary Sawers, Robert R. Eady, S. Samar Hasnain, PNAS, 102 No. 34, 12041-12046, 2005.
June 2005
Structural basis for nuclear import complex dissociation by RanGTPNuclear protein import is mediated mainly by the transport factor importin-β that binds cytoplasmic cargo, most often via the importin-α adaptor, and then transports it through nuclear pore complexes. This active transport is driven by disassembly of the import complex by nuclear RanGTP. The switch I and II loops of Ran change conformation with nucleotide state, and regulate its interactions with nuclear trafficking components. Importin-β consists of 19 HEAT repeats that stack to yield two C-shaped arches, linked together to form a helicoidal molecule that has considerable conformational flexibility.
Stewart's Group from MRC - LMB (Cambridge) has recently reported the X-ray crystal structure of full-length yeast importin-β (Kap95p or karyopherin-β) complexed with RanGTP, which provides a basis for understanding the crucial cargo-release step of nuclear import. Data were collected using NWSGC MAD 10 Station at SRS to a resolution of 2.7 A.
The structure of the Kap95p−RanGTP complex provides a basis for understanding how RanGTP dissociates the major nuclear protein import complex, by locking Kap95p in a conformation in which it is unable to exploit its flexibility to bind to different partners.
Full Reference:Nature 435, 693-696 (2 June 2005)
Soo Jae Lee 1, Yoshiyuki Matsuura 1, Sai Man Liu 1 and Murray Stewart 1
- MRC Laboratory of Molecular Biology, Hills Rd, Cambridge CB2 2QH, UK
Correspondence and requests for materials should be addressed to Murray Stewart ( Email:ms@mrc-lmb.cam.ac.uk).
February 2005
Station Manual IIAfter the changes below is probably time to re-write few chapters...
February 2005
New station control softwareThe new Graphical User interface has been delivered by the Software Group at Daresbury. This allows users to change wavelength without help from station scientists. The GUI will be started from a single command.. no more cogs and spanners...Early tests are very satisfactory.
February 2005
New beryllium windowThe good old beryllium window (0.5mm thick, used for commissioning) has now been replaced with of 0.2mm thickness. First tests already indicate a definite gain in flux over all the energy range.
28th January 2005
Cherie Booth QC Opens World-Leading Genomics Research Facility at CCLRC Daresbury LaboratoryCherie Booth QC formally opened Beamline 10. For more information's click here.
January 2005
Station Manual IThe station manual is now very close to completion. It can be read via the web or in hard-copy at the station (the blue book).
January 2005
Major software upgrade by MAR-USAM.Blum (MAR-USA) come to visit us early in January for a major software upgrade to the MAR-DTB and the detector. For users this means that bl10ccd will be more reliable during data collection and the scans for beam optimisation will be faster.
