Abstract. Gollumiellinae is proposed as a new subfamily for the Indo‐Pacific genera Gollumiella Hedqvist and Anorasema Bouc̆ek based on analyses of three ribosomal transcript gene regions (28S‐D2 and ‐D3, and 18S‐E23; 1262 aligned base pairs) sequenced for twenty‐eight genera and fifty‐four species of Eucharitidae, and twelve genera and nineteen species of Pteromalidae (Pteromalinae) and Perilampidae (Chrysolampinae and Perilampinae). Gollumiella and Anorasema have been treated as either a monophyletic or paraphyletic group within the Eucharitini (Hymenoptera: Eucharitidae). The monophyly of the Eucharitidae and a sister‐group relationship between Gollumiellinae and Oraseminae + Eucharitinae are supported strongly in parsimony and Bayesian analyses. The molecular phylogeny contradicts previous morphological hypotheses, in which Gollumiella and Anorasema are within Eucharitini. The strength of the molecular hypothesis is explored through evaluations of data alignments that are eye optimized, clustal‐x aligned, eye optimized but with gaps coded as a fifth base, and eye optimized and combined with morphological data. The oviposition behaviour and host associations of G. longipetiolata on tree ferns (Cyathea latebrosa, Cyatheaceae), and the morphology of the planidium and pupa are newly described. Eggs are deposited vertically, with the base anchored into the leaf or petiolar surface. Unlike other Eucharitidae, the eggs are not stalked, but rather tipped with a secretion that may act as an attractant for their ant host, Paratrechina sp. (Formicidae: Formicinae). Various morphological character state optimizations and their implications for convergent morphology, behaviour and host associations are discussed. All results using gene regions treated separately or combined with the morphological data reach the same conclusion: Anorasema + Gollumiella form the sister group of Oraseminae + Eucharitinae, and thus deserve subfamily status. This suggests that very distinct traits such as the fusion of the pronotum and prepectus in adults and the fusion of the first two tergites of the planidia are convergent apomorphies. Molecular data, when strongly supported, can provide new information to unravel convergent from synapomorphic changes, resulting in more robust hypotheses of relationship.
Multicopper oxidases (MCOs) are broadly distributed in all kingdoms of life and perform a variety of important oxidative reactions. These enzymes have potential biotechnological applications; however, the applications are impeded by low expression yields in traditional recombinant hosts, solubility issues, and poor copper cofactor assembly. As an alternative to traditional recombinant protein expression, we show the ability to use cell‐free protein synthesis (CFPS) to produce complex MCO proteins with high soluble titers. Specifically, we report the production of MCOs in an Escherichia coli‐based cell‐free transcription‐translation system. Total yields as high as 1.2 mg mL−1 were observed after a 20‐h batch reaction. More than 95% of the protein was soluble and activity was obtained by simple post‐CFPS addition of copper ions in the form of CuSO4. Scale‐up reactions were achieved from 15 to 100 µL without a decrease in productivity and solubility. CFPS titers were higher than in vivo expression titers and more soluble, avoiding the formation of inclusion bodies. Our work extends the utility of the cell‐free platform to the production of active proteins containing copper cofactors and demonstrates a simple method for producing MCOs.
The twin-arginine translocation (Tat) pathway is well known for its ability to export fully folded substrate proteins out of the cytoplasm of Gram-negative and Gram-positive bacteria. Studies of this mechanism in Escherichia coli have identified numerous transient protein-protein interactions that guide export-competent proteins through the Tat pathway. To visualize these interactions, we have adapted bimolecular fluorescence complementation (BiFC) to detect protein-protein interactions along the Tat pathway of living cells. Fragments of the yellow fluorescent protein (YFP) were fused to soluble and transmembrane factors that participate in the translocation process including Tat substrates, Tat-specific proofreading chaperones and the integral membrane proteins TatABC that form the translocase. Fluorescence analysis of these YFP chimeras revealed a wide range of interactions such as the one between the Tat substrate dimethyl sulfoxide reductase (DmsA) and its dedicated proofreading chaperone DmsD. In addition, BiFC analysis illuminated homo- and hetero-oligomeric complexes of the TatA, TatB and TatC integral membrane proteins that were consistent with the current model of translocase assembly. In the case of TatBC assemblies, we provide the first evidence that these complexes are co-localized at the cell poles. Finally, we used this BiFC approach to capture interactions between the putative Tat receptor complex formed by TatBC and the DmsA substrate or its dedicated chaperone DmsD. Our results demonstrate that BiFC is a powerful approach for studying cytoplasmic and inner membrane interactions underlying bacterial secretory pathways.
The folding of many cellular proteins occurs co-translationally immediately outside the ribosome exit tunnel, where ribosomal proteins and other associated factors coordinate the synthesis and folding of newly translated polypeptides. Here, we show that the large subunit protein L29, which forms part of the exit tunnel in Escherichia coli, is required for the productive synthesis of an array of structurally diverse recombinant proteins including the green fluorescent protein (GFP) and an intracellular single-chain Fv antibody. Surprisingly, the corresponding mRNA transcript level of these proteins was markedly less abundant in cells lacking L29, suggesting an unexpected regulatory mechanism that links defects in the exit tunnel to the expression of genetic information. To further highlight the importance of L29 in maintaining protein expression, we used mutagenesis and selection to obtain L29 variants that enhanced GFP expression. Overall, our results suggest that the ribosomal exit tunnel proteins may be key targets for optimizing the overproduction of active, structurally complex recombinant proteins in bacterial cells.
We report a highly specific, robust, and generic method for noncovalent labeling of cellular proteins with highly fluorescent core-shell silica nanoparticles termed C dots. Our approach uses short genetically engineered peptides with affinity for silica (GEPS) that are site-specifically introduced at the termini or in loops of cellular proteins. Because GEPS are absent from native cell surface proteins, GEPS-tagged recombinant proteins can be selectively and rapidly labeled with fluorescent C dots. To demonstrate the versatility of our method, we targeted 30 nm C dots to two structurally distinct integral outer membrane proteins in Escherichia coli, FhuA and OmpX. Efficient labeling was achieved in 15 min or less and was observed to be highly sensitive and specific. This strategy provides a powerful technique, comparable to other chemical and biological labeling strategies, for efficient and quantitative investigation of protein function in live biological cells.
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