Towards the development of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> as a cell factory for membrane proteins and protein complexes

Background  

The Gram-positive bacterium Bacillus subtilis is an important producer of high quality industrial enzymes and a few eukaryotic proteins. Most of these proteins are secreted into the growth medium, but successful examples of cytoplasmic protein production are also known. Therefore, one may anticipate that the high protein production potential of B. subtilis can be exploited for protein complexes and membrane proteins to facilitate their functional and structural analysis. The high quality of proteins produced with B. subtilis results from the action of cellular quality control systems that efficiently remove misfolded or incompletely synthesized proteins. Paradoxically, cellular quality control systems also represent bottlenecks for the production of various heterologous proteins at significant concentrations.     

Deployment of ACT antimalarials for treatment of malaria: challenges and opportunities

Background

In late 2002, the health authorities of Mozambique implemented sulphadoxine-pyrimethamine (SP)/amodiaquine (AQ) as first-line treatment against uncomplicated falciparum malaria. In 2004, this has been altered to SP/artesunate in line with WHO recommendations of using Artemisinin Combination Therapies (ACTs), despite the fact that all the neighbouring countries have abandoned SP-drug combinations due to high levels of SP drug resistance. In the study area, one year prior to the change to SP/AQ, SP alone was used to treat uncomplicated malaria cases. The study described here investigated the immediate impact of the change to SP on the frequency of SP and CQ resistance-related haplotypes in the Plasmodium falciparum genes Pfdhfr, Pfdhps and Pfcrt before and a year after the introduction of SP.

Methods

Samples were collected during two cross sectional surveys in early 2002 and 2003 involving 796 and 692 children one year or older and adults randomly selected living in Maciana, an area located in Manhiça district, Southern Mozambique. Out of these, 171 and 173 P. falciparum positive samples were randomly selected to measure the frequency of resistance- related haplotypes in Pfdhfr, Pfdhps and Pfcrt based on results obtained by nested PCR followed by sequence-specific oligonucleotide probe (SSOP)-ELISA.

Results

The frequency of the SP-resistance associated Pfdhps double mutant (SGEAA) haplotype increased significantly from 14% to 35% (P < 0.001), while the triple mutant Pfdhfr haplotype (CIRNI) remained high and only changed marginally from 46% to 53% (P = 0.405) after one year with SP as first-line treatment in the study area. Conversely, the combined Pfdhfr/Pfdhps quintuple mutant haplotype increased from 8% to 26% (P = 0.005). The frequency of the chloroquine resistance associated Pfcrt -CVIET haplotype was above 90% in both years.

Conclusion

These retrospective findings add to the general concern on the lifespan of the combination of SP/artesunate in Mozambique. The high frequency of quintuple Pfdhfr/Pfdhps haplotypes found here as early as 2002 most likely cause ideal conditions for the development of artesunate tolerance in the P. falciparum populations and may even endanger the sensitivity to the second-line drug, Coartem^®.     

An important step towards completing the rheumatoid arthritis cycle

In the previous issue of Arthritis Research & Therapy data are presented showing that circulating immune complexes containing citrullinated fibrin(ogen) are present in anti-citrullinated protein antibody-positive rheumatoid arthritis patients, and that such immune complexes co-localize with complement factor C3 in the rheumatoid synovium. These results corroborate the idea that citrullination is intimately involved in the pathophysiology of rheumatoid arthritis and complete our model (the rheumatoid arthritis cycle) for the development and chronic nature of this disease.     

Conservation of protein phosphorylation sites within gene families and across species

Recent large scale phosphoproteomics studies have helped identify many phosphorylation sites of both membrane and soluble proteins. In most cases the relevance of specific sites has yet to be established whereas in a small number of cases their potency in modulating protein activity is evident. With the increasing amount of data it is becoming clear that phosphosites are often conserved within protein families, pointing to generic regulatory mechanisms. In addition, such mechanisms may be conserved across species. In this addendum evidence is presented for these phenomena occurring in rice and Arabidopsis.Key words: Arabidopsis, kinase, phosphoproteomics, rice     

Potential therapeutic implications of new insights into respiratory syncytial virus disease

Viral bronchiolitis is the most common cause of hospitalization in infants under 6 months of age, and 70% of all cases of bronchiolitis are caused by respiratory syncytial virus (RSV). Early RSV infection is associated with respiratory problems such as asthma and wheezing later in life. RSV infection is usually spread by contaminated secretions and infects the upper then lower respiratory tracts. Infected cells release proinflammatory cytokines and chemokines, including IL-1, tumor necrosis factor-α, IL-6, and IL-8. These activate other cells and recruit inflammatory cells, including macrophages, neutrophils, eosinophils, and T lymphocytes, into the airway wall and surrounding tissues. The pattern of cytokine production by T lymphocytes can be biased toward 'T-helper-1' or 'T-helper-2' cytokines, depending on the local immunologic environment, infection history, and host genetics. T-helper-1 responses are generally efficient in antiviral defense, but young infants have an inherent bias toward T-helper-2 responses. The ideal intervention for RSV infection would be preventive, but the options are currently limited. Vaccines based on protein subunits, live attenuated strains of RSV, DNA vaccines, and synthetic peptides are being developed; passive antibody therapy is at present impractical in otherwise healthy children. Effective vaccines for use in neonates continue to be elusive but simply delaying infection beyond the first 6 months of life might reduce the delayed morbidity associated with infantile disease.     

Structural characterization of genomes by large scale sequence-structure threading

Background  

Using sequence-structure threading we have conducted structural characterization of complete proteomes of 37 archaeal, bacterial and eukaryotic organisms (including worm, fly, mouse and human) totaling 167,888 genes.     

Pyridoxamine, an inhibitor of advanced glycation reactions, also inhibits advanced lipoxidation reactions. Mechanism of action of pyridoxamine

Maillard or browning reactions lead to formation of advanced glycation end products (AGEs) on protein and contribute to the increase in chemical modification of proteins during aging and in diabetes. AGE inhibitors such as aminoguanidine and pyridoxamine (PM) have proven effective in animal model and clinical studies as inhibitors of AGE formation and development of diabetic complications. We report here that PM also inhibits the chemical modification of proteins during lipid peroxidation (lipoxidation) reactions in vitro, and we show that it traps reactive intermediates formed during lipid peroxidation. In reactions of arachidonate with the model protein RNase, PM prevented modification of lysine residues and formation of the advanced lipoxidation end products (ALEs) N(epsilon)-(carboxymethyl)lysine, N(epsilon)-(carboxyethyl)lysine, malondialdehyde-lysine, and 4-hydroxynonenal-lysine. PM also inhibited lysine modification and formation of ALEs during copper-catalyzed oxidation of low density lipoprotein. Hexanoic acid amide and nonanedioic acid monoamide derivatives of PM were identified as major products formed during oxidation of linoleic acid in the presence of PM. We propose a mechanism for formation of these products from the 9- and 13-oxo-decadienoic acid intermediates formed during peroxidation of linoleic acid. PM, as a potent inhibitor of both AGE and ALE formation, may prove useful for limiting the increased chemical modification of tissue proteins and associated pathology in aging and chronic diseases, including both diabetes and atherosclerosis.