Bacterial cultures that can count up to three

In a recent issue of Science, Friedland et al. report bacterial cultures that can count up to 3 - albeit without knowing it themselves. What they count are pulses of arabinose, a sugar - and they report via fluorescence signal.

Journal club 15/6/2009

In their paper "Chaperonin overexpression promotes genetic variation and enzyme evolution", Tokuriki and Tawfik show protein stability is a major constraint in protein evolution. Chaperonin over-expression can, at least partially, mitigate it, see Nature 459, 668-673. In the same issue of Nature, Mueller et al. present the structure of an alpha-helical toxin pore and propose a detailed mechanism for pore-formation, see pages 726-730.

Modern humans come from East Africa, near de Red Sea

As reported in the issue of Science of 1 May 2009, p. 575

by Ann Gibbons in "Africans' Deep Genetic Roots Reveal Their Evolutionary Story":

The data also confirm earlier research indicating that the source population for the out-of-Africa migration of modern humans came from east Africa near the Red Sea.

Dangers in the lab

It is always good to read about dangers in the lab, and Nature in it's issue of 2 April has a nice feature about it on page 664-665 (subscription necessary). Note the following passage about the dangers of a mercury compound:
Chemist Karen Wetterhahn spilt a drop of dimethylmercury on her gloved hand in 1996 at Dartmouth College in New Hampshire. At the time, it was not known that the chemical passes through latex, so she did not realize it had reached her skin. She fell ill five months later and died within the year.

NMR and crystallography, or rather, crystallography and NMR.

I like the ultimate paragraph of the Highlight written by Burkhard Luy in Angewandte Chemie Int. Ed. (2007, volume 46, pages 4214-4216), it illustrates the complementarity of X-ray crystallography and NMR spectroscopy very well:

"With the NMR techniques developed over the past decade and the availability of corresponding crystal structures, molecular complexes of nearly unlimited size seem to be amenable to liquid-state dynamics measurements. These results are an important step in understanding the modes of operation of complicated molecular machines in biological systems."

Note that the crystal structure of the 20S proteasome complex was necessary in order to be able to interpret the NMR signals of the particle, and that the NMR results shed light on dynamic properties which crystallography had not measured.
Also note the NMR work was expensive, requiring extensive labeling, mutation to make a monomeric version - so it would presumably be only worth doing this for very important macromolecular complexes.

Tracing a protein at 5.5 Å resolution

In a paper published in Nature 26 March 2009 (p. 475), Pomeranz Krummel et al. describe the structure of human spliceosomal U1 snRNP at 5.5 Å resolution. what struck me is how they traced the structure of one of the component proteins: via mutating individually all methionine residues of the Se-Met versions of the protein, crystallising and collecting data of all variant complexes and locating the said methionines in anomalous difference maps. A real tour-de-force!

p321

P321 is probably my favourite crystallographic spacegroup, as viral fibre proteins also seem to like to crystallise "in it".

The name may be seen as a blatant almost-copy of the much more professional protein crystallography blog www.p212121.com and it perhaps is. In any case, this is going to be much more low-key and probably have much more infrequent entries...