Plasticity within the barrel domain of BamA mediates a hybrid-barrel mechanism by BAM.

In Gram-negative bacteria, the biogenesis of β-barrel outer membrane proteins is mediated by the β-barrel assembly machinery (BAM). The mechanism employed by BAM is complex and so far- incompletely understood. Here, we report the structures of BAM in nanodiscs, prepared using polar lipids and native membranes, where we observe an outward-open state.

Crystal structures of S-HPCDH reveal determinants of stereospecificity for R- and S-hydroxypropyl-coenzyme M dehydrogenases.

(R)- and (S)-hydroxypropyl-coenzyme M dehydrogenases (R- and S-HPCDH) are stereospecific enzymes that are central to the metabolism of propylene and epoxide in Xanthobacter autotrophicus. The bacterium produces R- and S-HPCDH simultaneously to facilitate transformation of R- and S-enantiomers of epoxypropane to a common achiral product 2-ketopropyl-CoM (2-KPC). Both R- and S-HPCDH are highly specific for their respective substrates as each enzyme displays less than 0.

Rapid evolution in response to introduced predators II: the contribution of adaptive plasticity.

Background: Introductions of non-native species can significantly alter the selective environment for populations of native species, which can respond through phenotypic plasticity or genetic adaptation. We examined phenotypic and genetic responses of Daphnia populations to recent introductions of non-native fish to assess the relative roles of phenotypic plasticity versus genetic change in causing the observed patterns. The Daphnia community in alpine lakes throughout the Sierra Nevada of California (USA) is ideally suited for investigation of rapid adaptive evolution because there are multiple lakes with and without introduced fish predators.