We report a draft sequence for the genome of the domesticated silkworm (Bombyx mori), covering 90.9% of all known silkworm genes. Our estimated gene count is 18,510, which exceeds the 13,379 genes reported for Drosophila melanogaster. Comparative analyses to fruitfly, mosquito, spider, and butterfly reveal both similarities and differences in gene content.

COP10 is a ubiquitin-conjugating enzyme variant (UEV), which is thought to act together with COP1, DET1, and the COP9 signalosome (CSN) in Arabidopsis to repress photomorphogenesis. Here, we demonstrate that COP10 interacts with ubiquitin-conjugating enzymes (E2s) in vivo, and can enhance their activity in vitro, an activity distinct from previous characterized UEVs such as MMS2 and UEV1. Furthermore, we show that COP10 forms a complex with UV-damaged DNA-binding protein 1a (DDB1a) and de-etiolated 1 (DET1), and physically interacts with COP1 and the CSN. Purified CDD (COP10, DDB1, DET1) complex also shows enhancement of E2 activity (UEA) similar to that observed with COP10 itself. Our data suggests that COP10, along with COP1 and the CSN, promotes the degradation of positive regulators of photomorphogenesis, such as the transcription factor HY5, via the ubiquitin/26S proteasome system. Thus, the CDD complex may act as a ubiquitylation-promoting factor to regulate photomorphogenesis.

SummaryBrassinosteroids induce H2O2 accumulation from RBOH1-NADPH oxidase, which first induces ABA biosynthesis and stress tolerance, in turn leading to prolonged H2O2 production in both apoplast and chloroplast and stress tolerances.

The TEM-1 β-lactamase confers bacterial resistance to penicillin antibiotics and has acquired mutations that permit the enzyme to hydrolyze extended spectrum cephalosporins or avoid inactivation by β-lactamase inhibitors. However, many of these substitutions have been shown to reduce activity against penicillin antibiotics and/or result in a loss of stability for the enzyme. In order to gain more information concerning the trade-offs associated with active site substitutions, a genetic selection was used to find second site mutations which partially restore ampicillin resistance levels conferred by an R244A active site TEM-1 β-lactamase mutant. An L201P substitution distant from the active site was identified that enhanced ampicillin resistance levels and increased protein expression levels of the R244A TEM-1 mutant. The L201P substitution also increases the ampicillin resistance levels and restores expression levels of a poorly expressed TEM-1 mutant with a coredisrupting substitution. In vitro thermal denaturation of purified protein indicated that the L201P mutation increases the T m of the TEM-1 enzyme. The X-ray structure of the L201P TEM-1 mutant was determined to gain insight into the increase in enzyme stability. The proline substitution occurs at the N-terminus of an α-helix and may stabilize the enzyme by reducing the helix dipole as well as lowering the conformational entropy cost of folding due to the reduced number of conformations available in the unfolded state. Collectively the data suggest that L201P promotes tolerance of some deleterious TEM-1 mutations by enhancing protein stability of these mutants.

No abstract