Construction and evaluation of a safe, live, oral Vibrio cholerae vaccine candidate, IEM108 Liang, W. et al. Infect. Immun. 71, 5498–5504 (2003)

Vaccination against cholera is a feasible prevention strategy — but because toxin genes are present on a lysogenic Vibrio bacteriophage (CTXΦ), any live attenuated vaccine strain should ideally be phage resistant. Otherwise, phage infection could make a safe vaccine strain toxigenic. A new candidate vaccine strain — IEM008 — incorporates a gene that represses the replication and integration functions of the CTXΦ phage. IEM008 protected rabbits against challenge with 4 wild-type strains of V. cholerae in rabbits and is an excellent candidate for field tests.

Fungal ecology

Seasonal dynamics of previously unknown fungal lineages in tundra soils Schadt, C. W. et al. Science 301, 1359–1361 (2003)

Exciting findings have revealed that undersnow soils are physiologically active. The most surprising outcome of this study was that huge numbers of mainly novel fungi accounted for most of the active biomass. The community structure changed dramatically between summer and winter months, but fungal activity dominated throughout. New lineages of identified fungi will undoubtedly revolutionize our knowledge of tundral ecosystems.


LysM domain receptor kinases regulating rhizobial Nod factor-induced infection Limpens, E et al. Science Aug 28 2003 (doi:10.1126/science.1090074)

Rhizobial bacteria establish symbiotic nitrogen-fixing nodules on legume roots in a strictly host-specific manner. Limpens et al. identified 2 genes in a model legume — LYK3/4 — that were essential for establishing nodules. Rhizobial species export so-called Nod factors, which induce host plant nodulation. The authors speculate that LysM domains — known to recognize peptidoglycan-like structures — in LYK3/4 discriminate between different Nods.

Bacterial secretion

Structural determinants of SecB recognition by SecA in bacterial protein translocation Zhou, J. & Xu, Z. Nature Struct. Biol. Sept 28 2003 (doi:10.1038/nsb980)

Secretion across the Gram-negative bacterial inner membrane is mainly through the Sec system. New structural information for SecB — a cytosolic chaperone that delivers proteins to the secretion machine SecA — shows that a SecA zinc-binding motif is crucial for the SecA–SecB interaction. They propose that a SecB tetramer is positioned beneath SecA to deliver proteins to the SecA machine.