Genetics

Temperature-sensitive yeast mutants

Li et al. present a collection of temperature-sensitive mutants of almost half of the essential genes in yeast, in a genetic background appropriate for interaction screening using the synthetic genetic array method. Barcoding of the collection permits chemical-genetic suppression screening and combination with fluorescent markers of subcellular structures enables high-content screening of double-mutant phenotypes in single cells.

Li, Z. et al. Nat. Biotechnol. 29, 361–367 (2011).

Mass Spectrometry

HCD without a dedicated collision cell

In proteomics applications, especially for de novo sequencing and identifying protein modifications, peptides can be efficiently fragmented by tandem mass spectrometry via high-energy collision-induced dissociation (HCD) involving a specialized collision cell. McAlister et al. now show that HCD can be performed in the ion injection pathway of any mass spectrometer with a common atmospheric inlet, without a dedicated collision cell.

McAlister, G.C. et al. Mol. Cell. Proteomics advance online publication (10 March 2011).

Genomics

GROMIT looks at the regulatory genome

To find regulatory elements in the mouse genome, Ruf et al. developed genome regulatory organization mapping with integrated transposons (GROMIT), a strategy that uses the Sleeping Beauty transposon containing a lacZ reporter gene driven by a minimal promoter that responds to nearby enhancers. Following the expression patterns of the reporters in single-integrant mouse lines, they found transcriptional activity all over the chromosomes. Currently available lines cover about 10% of the mouse genome.

Ruf, S. et al. Nat. Genet. 43, 379–386 (2011).

Chemical Biology

Protein control with a photoactivatable split intein

Binschik et al. introduce a photoactivatable split-intein system for studying protein function in the living cell. Attaching one half of the split intein to the pathogenic protein staphylocoagulase modulated its binding to prothrombin in human blood plasma. Upon light activation, a bulky caging group is cleaved off the other half of the split intein, facilitating the splicing reaction, and resulting in the cleavage of staphylocoagulase and the restoration of its activity.

Binschik, J. et al. Angew. Chem. Int. Edn. 50, 3249–3252 (2011).

Neuroscience

Addressing errors in patch clamping

The cell-attached patch clamp configuration is useful for investigating the functional properties of voltage-activated ion channels without substantially disturbing the rest of the cell. Williams and Wozny carefully examine the errors associated with such measurements and introduce simple correction procedures; in particular they found that the amplitude and kinetics of ion-channel activity can be distorted by transmembrane voltage changes associated with current flow.

Williams, S.R. & Wozny, C. Nat. Commun. 2, 242 (2011).