Bendless is essential for PINK1-Park mediated Mitofusin degradation under mitochondrial stress caused by loss of LRPPRC.

Cells under mitochondrial stress often co-opt mechanisms to maintain energy homeostasis, mitochondrial quality control and cell survival. A mechanistic understanding of such responses is crucial for further insight into mitochondrial biology and diseases. Through an unbiased genetic screen in Drosophila, we identify that mutations in lrpprc2, a homolog of the human LRPPRC gene that is linked to the French-Canadian Leigh syndrome, result in PINK1-Park activation. While the PINK1-Park pathway is well known to induce mitophagy, we show that PINK1-Park regulates mitochondrial dynamics by inducing the degradation of the mitochondrial fusion protein Mitofusin/Marf in lrpprc2 mutants. In our genetic screen, we also discover that Bendless, a K63-linked E2 conjugase, is a regulator of Marf, as loss of bendless results in increased Marf levels. We show that Bendless is required for PINK1 stability, and subsequently for PINK1-Park mediated Marf degradation under physiological conditions, and in response to mitochondrial stress as seen in lrpprc2. Additionally, we show that loss of bendless in lrpprc2 mutant eyes results in photoreceptor degeneration, indicating a neuroprotective role for Bendless-PINK1-Park mediated Marf degradation. Based on our observations, we propose that certain forms of mitochondrial stress activate Bendless-PINK1-Park to limit mitochondrial fusion, which is a cell-protective response.

A comparison between MBP- and NT* as N-terminal fusion partner for recombinant protein production in E. coli.

Advances in structural biology have been fueled in part by developing techniques for large-scale heterologous expression and purification of proteins. Nevertheless, this step is still a bottleneck in biophysical studies of many proteins. Often, fusion proteins are used to increase expression levels, solubility, or both. Here, we compare a recently reported fusion tag, NT*, with Maltose Binding Protein (MBP), a well-known fusion tag and solubility enhancer. NT* shows high expression and solubility when used as an N-terminal fusion partner for several aggregation-prone peptides. Its efficacy in enhancing the solubility of aggregation-prone globular proteins has, however, not been tested. We find here that although the overall expression levels for NT* fusions are much higher than those for the MBP fusion, MBP was far superior for enhancing the solubility of the passenger protein. Nevertheless, the effective yield after purification from the soluble fraction of both MBP-fusion and NT*-fusion was comparable, mainly due to higher expression levels in NT*-fusion and a smaller fraction of the passenger protein net weight being locked in the fusion protein. We conclude that NT* is an excellent fusion tag to improve the overall expression of globular proteins but does not increase the passenger protein's solubility compared to MBP. Proteins that are partially soluble or can be refolded in-vitro will significantly benefit from N-terminal NT* fusions. MBP, however, still remains one of the very few options for an N-terminal fusion if the solubility of the protein after expression is critical for preserving its proper fold or activity.

Structure-function characterization of an insecticidal protein GNIP1Aa, a member of an MACPF and ß-tripod families.

The crystal structure of the Gram-negative insecticidal protein, GNIP1Aa, has been solved at 2.5-Å resolution. The protein consists of two structurally distinct domains, a MACPF (membrane attack complex/PerForin) and a previously uncharacterized type of domain. GNIP1Aa is unique in being a prokaryotic MACPF member to have both its structure and function identified. It was isolated from a Chromobacterium piscinae strain and is specifically toxic to Diabrotica virgifera virgifera larvae upon feeding. In members of the MACPF family, the MACPF domain has been shown to be important for protein oligomerization and formation of transmembrane pores, while accompanying domains define the specificity of the target of the toxicity. In GNIP1Aa the accompanying C-terminal domain has a unique fold composed of three pseudosymmetric subdomains with shared sequence similarity, a feature not obvious from the initial sequence examination. Our analysis places this domain into a protein family, named here ß-tripod. Using mutagenesis, we identified functionally important regions in the ß-tripod domain, which may be involved in target recognition.

Discovery of a novel insecticidal protein from Chromobacterium piscinae, with activity against Western Corn Rootworm, Diabrotica virgifera virgifera.

Western corn rootworm (WCR), Diabrotica virgifera virgifera, is one of the most significant pests of corn in the United States. Although transgenic solutions exist, increasing resistance concerns make the discovery of novel solutions essential. In order to find a novel protein with high activity and a new mode of action, a large microbial collection was surveyed for toxicity to WCR using in vitro bioassays. Cultures of strain ATX2024, identified as Chromobacterium piscinae, had very high activity against WCR larvae. The biological activity from the strain was purified using chromatographic techniques and fractions were tested against WCR larvae. Proteins in the final active fraction were identified by mass spectrometry and N-terminal sequencing and matched to the genome of ATX2024. A novel 58.9kDa protein, identified by this approach, was expressed in a recombinant expression system and found to have specific activity against WCR. Transgenic corn events containing this gene showed good protection against root damage by WCR, with average scores ranging between 0.01 and 0.04 on the Iowa State node injury scale. Sequence analysis did not reveal homology to any known insecticidal toxin, suggesting that this protein may act in a novel way to control WCR. The new WCR active protein is named GNIP1Aa, for Gram Negative Insecticidal Protein.

Evaluation of neuroimmunomodulatory activity of recombinant human interferon α.

OBJECTIVE: Recombinant human interferon (rhIFN)-α is a potent immunoregulator having a wide range of therapeutic applications. In the present study, rhIFN-α was evaluated for its neuroimmunomodulatory activity. METHOD: Dose-dependent gene expression of cytokines and chemokines in the brain of rhIFN-administered mice was studied using real-time SYBR green PCR. RESULTS: Statistically significant increase in expression levels of tumor necrosis factor-α, interleukin (IL)-6, IL-1ß and IFN-γ were observed. CONCLUSION: The findings indicate that rhIFN-α may be used at an optimized dose to cause appropriate neuromodulation of cytokine/chemokine secretion that can aid in the development of therapeutic approaches for many infectious diseases of the central nervous system for which therapies are lacking.

EYA protein complex is required for Wntless retrograde trafficking from endosomes to Golgi.

Retrograde transport of WLS (Wntless) from endosomes to trans-Golgi network (TGN) is required for efficient Wnt secretion during development. However, the molecular players connecting endosomes to TGN during WLS trafficking are limited. Here, we identified a role for Eyes Absent (EYA) proteins during retrograde trafficking of WLS to TGN in human cell lines. By using worm, fly, and zebrafish models, we found that the EYA-secretory carrier-associated membrane protein 3 (SCAMP3) axis is evolved in vertebrates. EYAs form a complex and interact with retromer on early endosomes. Retromer-bound EYA complex recruits SCAMP3 to endosomes, which is necessary for the fusion of WLS-containing endosomes to TGN. Loss of EYA complex or SCAMP3 leads to defective transport of WLS to TGN and failed Wnt secretion. EYA mutations found in patients with hearing loss form a dysfunctional EYA-retromer complex that fails to activate Wnt signaling. These findings identify the EYA complex as a component of retrograde trafficking of WLS from the endosome to TGN.

Assessment of efficacy of palm polymerase chain reaction with microscopy, rapid diagnostic test and conventional polymerase chain reaction for diagnosis of malaria.

Purpose: Sensitive, specific, rapid and cost-effective technique for malaria diagnosis is need of the hour. Microscopy has been the gold standard for malaria diagnosis, but its interpersonnel variability and lack of sensitivity make it subjective test. Conventional polymerase chain reaction (cPCR) has proven to be sensitive technique, but costly and time-consuming. Considering these factors, we have compared microscopy and cPCR with newly derives ultra-fast, portable PCR machine called Palm PCR. Materials and Methods: Palm PCR is arranged with three heat blocks precisely made for three stages of PCR cycles with 34 min for 1100 bp Plasmodium genus outer primer to amplify and 10 min each for Plasmodium falciparum and Plasmodium vivax inner primers of 120 bp and 205 bp, respectively. A total of 191 suspected samples were processed and evaluated using receiver operating characteristic (ROC) curve analysis. Results: The area under ROC curve analysis for Palm PCR with reference standard microscopy for P. falciparum, P. vivax and Plasmodium was 0.8969, 0.9121 and 0.9116, respectively, and with reference standard cPCR was 1.0 for all of them. ROC curve area close of suggests that Palm PCR can be as significant as cPCR in malaria diagnosis. In fact, ultra-rapid amplification with same precision makes Palm PCR better technique than cPCR. Conclusion: Palm PCR is sensitive, rapid and works on battery with simple laboratory facility requirements. Portable electrophoresis and transilluminator combined with Palm PCR could be implemented as an important diagnostic tool in resource-limited and rural areas. Similar studies with wider parameters in rural areas will help us evaluate and maybe establish Palm PCR as PCR platform of choice for such specific set-ups.