Efficient production of Clostridium botulinum exotoxin C3 in bacteria: a screening method to optimize production yields

Clostridium botulinum exoenzyme C3 is responsible for the inactivation of members of the Rho GTPase family that are implicated in actin-cytoskeleton reorganization. This property has been extensively used in the field to investigate the functionality of the Rho GTPases. However, systematic analysis of Rho GTPase functions requires large amounts of such inhibitors and consequently an optimization of the production yield of these proteins. Bacterial production of soluble proteins often requires a refolding step that noticeably affects the production yields and necessitates additional experiments to verify functional activity. This is particularly true for TAT-C3, the production yields of which are generally low. In this report, we describe a rapid and efficient method for the production of soluble C3 exoenzyme developed by screening a collection of bacterial strains. The recombinant C3 protein was fused to the TAT protein-transduction domain from HIV, to allow protein delivery into cells, and to a hexahistidine tag, that permitted purification by Nickel affinity chromatography. We have demonstrated the production of large amounts of soluble and functional protein using the bacterial strain AD494 (DE3)pLysS. This rapid and efficient method for the production of soluble C3 exoenzyme could also be useful for the production of other proteins with solubility problems.     

The Arg482His mutation in the beta-galactosidase gene is responsible for a high frequency of GM1 gangliosidosis carriers in a Cypriot village

GM1 gangliosidosis is a lysosomal storage disorder caused by deficiency of beta-galactosidase. It is mainly characterized by progressive neurodegeneration, and in its most severe infantile form, it leads to death before the age of 4. The GLB1 gene gives rise to two alternatively spliced mRNAs that encode the beta-galactosidase and the elastin binding protein (EBP). The diagnosis of two patients with the infantile form of GM1 gangliosidosis and 11 carriers in a small mountainous village in Cyprus prompted us to carry out a study in order to establish the frequency of carriers in the village and identify the mutations involved. Carrier detection was initially based on the measurement of beta-galactosidase activity in leucocytes. Among 85 random samples from the village, 10 were classified as carriers. Sequencing of the GLB1 gene in a Cypriot patient identified the missense mutation c.1445G>A (p.Arg482His) in the homozygous state. Seven of the 10 carriers identified using the enzyme assay were found to carry the same mutation by NspI restriction enzyme analysis. The three individuals who were negative for the c.1445G>A had borderline enzyme results and were probably wrongly classified as carriers. The frequency of GM1 gangliosidosis carriers in this village is approximately 8% (1:12). Western blot analysis showed a marked decrease of the 64-kDa mature form of the enzyme protein and a similar reduction of the 67-kDa EBP. Our results indicate that the c.1445G>A mutation, which appears to be responsible for all GM1 gangliosidosis alleles in this Cypriot village, affects protein conformation.     

Nuclear transfer: a new tool for reproductive biotechnology in cattle

Recent evolutions of somatic cloning by nuclear transfer are reported, especially in the bovine species where potential applications are underway for biomedicine in association with transgenesis, or for agriculture by improving livestock. The overall efficiency of this biotechnology remains low in terms of viable offspring, but significant progress has been achieved on the different steps of the technique. However, the in vivo development of bovine blastocysts derived from somatic nuclear transfer is characterised by some important features that lead to the "cloning syndrome". Important losses occur during the peri-implantation period and further late foetal loss is observed in association with the Large Offspring Syndrome. About 60-70% of the cloned calves born survive normally to the adult stage and present an apparently normal physiology. Recent data already available on bovine somatic clones of both sexes indicate that they have a zootechnical performance similar to non cloned animals and they are able to reproduce normally without the pathologies associated to cloning thus confirming that the deviations observed in clones are of epigenetic origin and not transmitted to the progeny.     

Nanoarchaea: representatives of a novel archaeal phylum or a fast-evolving euryarchaeal lineage related to Thermococcales?

Background  

Cultivable archaeal species are assigned to two phyla - the Crenarchaeota and the Euryarchaeota - by a number of important genetic differences, and this ancient split is strongly supported by phylogenetic analysis. The recently described hyperthermophile Nanoarchaeum equitans, harboring the smallest cellular genome ever sequenced (480 kb), has been suggested as the representative of a new phylum - the Nanoarchaeota - that would have diverged before the Crenarchaeota/Euryarchaeota split. Confirming the phylogenetic position of N. equitans is thus crucial for deciphering the history of the archaeal domain.     

Increase of mitochondrial DNA content and transcripts in early bovine embryogenesis associated with upregulation of mtTFA and NRF1 transcription factors

Background  

Recent work has shown that mitochondrial biogenesis and mitochondrial functions are critical determinants of embryonic development. However, the expression of the factors controlling mitochondrial biogenesis in early embryogenesis has received little attention so far.     

Ubiquitylation of neuronal nitric-oxide synthase by CHIP, a chaperone-dependent E3 ligase

It is established that neuronal nitric-oxide synthase (nNOS) is ubiquitylated and proteasomally degraded. The proteasomal degradation of nNOS is enhanced by suicide inactivation of nNOS or by the inhibition of hsp90, which is a chaperone found in a native complex with nNOS. In the current study, we have examined whether CHIP, a chaperone-dependent E3 ubiquitin-protein isopeptide ligase that is known to ubiquitylate other hsp90-chaperoned proteins, could act as an ubiquitin ligase for nNOS. We found with the use of HEK293T or COS-7 cells and transient transfection methods that CHIP overexpression causes a decrease in immunodetectable levels of nNOS. The extent of the loss of nNOS is dependent on the amount of CHIP cDNA used for transfection. Lactacystin (10 microM), a selective proteasome inhibitor, attenuates the loss of nNOS in part by causing the nNOS to be found in a detergent-insoluble form. Immunoprecipitation of the nNOS and subsequent Western blotting with an anti-ubiquitin IgG shows an increase in nNOS-ubiquitin conjugates because of CHIP. Moreover, incubation of nNOS with a purified system containing an E1 ubiquitin-activating enzyme, an E2 ubiquitin carrier protein conjugating enzyme (UbcH5a), CHIP, glutathione S-transferase-tagged ubiquitin, and an ATP-generating system leads to the ubiquitylation of nNOS. The addition of purified hsp70 and hsp40 to this in vitro system greatly enhances the amount of nNOS-ubiquitin conjugates, suggesting that CHIP is an E3 ligase for nNOS whose action is facilitated by (and possibly requires) its interaction with nNOS-bound hsp70.