Regulation of chaperone/effector complex synthesis in a bacterial type III secretion system

Type III protein secretion systems (T3SSs), which have evolved to deliver bacterial proteins into nucleated cells, are found in many species of Gram-negative bacteria that live in close association with eukaryotic hosts. Proteins destined to travel this secretion pathway are targeted to the secretion machine by customized chaperones, with which they form highly structured complexes. Here, we have identified a mechanism that co-ordinates the expression of the Salmonella Typhimurium T3SS chaperone SicP and its cognate effector SptP. Translation of the effector is coupled to that of its chaperone, and in the absence of translational coupling, an inhibitory RNA structure prevents translation of sptP. The data presented here show how the genomic organization of functionally related proteins can have a significant impact on the co-ordination of their expression.     

HDAC6 Regulates Mutant SOD1 Aggregation through Two SMIR Motifs and Tubulin Acetylation

Histone deacetylase 6 (HDAC6) is a tubulin deacetylase that regulates protein aggregation and turnover. Mutations in Cu/Zn superoxide dismutase (SOD1) linked to familial amyotrophic lateral sclerosis (ALS) make the mutant protein prone to aggregation. However, the role of HDAC6 in mutant SOD1 aggregation and the ALS etiology is unclear. Here we report that HDAC6 knockdown increased mutant SOD1 aggregation in cultured cells. Different from its known role in mediating the degradation of poly-ubiquitinated proteins, HDAC6 selectively interacted with mutant SOD1 via two motifs similar to the SOD1 mutant interaction region (SMIR) that we identified previously in p62/sequestosome 1. Expression of the aggregation-prone mutant SOD1 increased α-tubulin acetylation, and the acetylation-mimicking K40Q α-tubulin mutant promoted mutant SOD1 aggregation. Our results suggest that ALS-linked mutant SOD1 can modulate HDAC6 activity and increase tubulin acetylation, which, in turn, facilitates the microtubule- and retrograde transport-dependent mutant SOD1 aggregation. HDAC6 impairment might be a common feature in various subtypes of ALS.     

Marine antifoulants from bifurcaria bifurcata (phaeophyceae,cystoseiraceae) and other brown macroalgae

In this study, the antifouling activity of a series of extracts and linear diterpenes isolated from Bifurcaria bifurcata (Velley) Ross, a common brown alga of the Atlantic shores of Europe, and derivatives of these compounds was investigated. Antifouling assays with crude extracts from other brown algae, found abundantly along the coast of South Africa (Bifurcaria brassicaeformis, Bifurcariopsis capensis), the Atlantic shores of Europe (Halidrys siliquosa) and the coast of Mediterranean sea (Cladostephus verticillatus, Halopteris scoparia), are also reported. The fractions were tested in laboratory assays against representative species of the major groups of fouling organisms, viz. bacteria, fungi, diatoms, spores and zygotes of macroalgae and the blue mussel Mytilus edulis. Several components showed promising levels of activity. The high, albeit variable, level of antifouling activity suggests a potential for novel active ingredients in antifouling preparations.     

Observations of follicle cell processes in a holocephalan

The presence of follicular cellular processes (FCP) that cross the zona pellucida, has been recorded in the ovarian follicles of Callorhinchus callorhynchus. This constitutes the first report describing the presence of these structures in a species of the Holocephali. Considering that FCPs have only previously been reported in the Selachii, these findings suggest that FCPs could have been lost by the Batoidea after their divergence, around 280 M B.P.     

<Emphasis Type="Italic">Pneumocystis jirovecii</Emphasis> and Cystic Fibrosis in Brittany,France

Pneumocystis jirovecii is a transmissible fungus with a high pulmonary tropism. The prevalence of P. jirovecii in patients with cystic fibrosis (CF) has been estimated in Germany at 7.4%, in Spain at 21.5% and in Brazil at 38.2%. Data on the prevalence of P. jirovecii in CF patients in France remain scarce, particularly in Brittany, where the prevalence of CF is high (from 1/1600 to 1/4500). Our objectives were to determine the prevalence of colonization of the airways by P. jirovecii in Brittany in CF patients monitored at the “Centre de Ressources et de Compétences de la Mucoviscidose (CRCM)” of Rennes compared to that previously observed at the CRCM of Roscoff–Brest. Sputa from 86 patients (178 specimens) followed in Rennes were analyzed retrospectively. The detection of P. jirovecii was performed using real-time PCR targeting the gene encoding the mitochondrial large subunit of ribosomal RNA. Pneumocystis jirovecii DNA was detected in 3/86 patients (3.5%) monitored at Rennes, whereas it had previously been detected in 1/76 patients (1.3%) monitored at Roscoff–Brest, thus showing an overall prevalence of 2.5% in Brittany. These results obtained from two Breton centers taken together show that P. jirovecii prevalence in patients with CF in Brittany is lower than those observed in Germany, Spain, Brazil or in other regions of France. This study is a preliminary step in determining the risk factors for P. jirovecii acquisition, its epidemiological and clinical significance in CF patients through a prospective multicenter study.     

Decoding a Salmonella Typhi Regulatory Network that Controls Typhoid Toxin Expression within Human Cells

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