SepF supports the recruitment of the DNA translocase SftA to the Z-ring

In many bacteria, cell division begins before the sister chromosomes are fully segregated. Specific DNA translocases ensure that the chromosome is removed from the closing septum, such as the transmembrane protein FtsK in Escherichia coli. Bacillus subtilis contains two FtsK homologues, SpoIIIE and SftA. SftA is active during vegetative growth whereas SpoIIIE is primarily active during sporulation and pumps the chromosome into the spore compartment. FtsK and SpoIIIE contain several transmembrane helices, however, SftA is assumed to be a cytoplasmic protein. It is unknown how SftA is recruited to the cell division site. Here we show that SftA is a peripheral membrane protein, containing an N-terminal amphipathic helix that reversibly anchors the protein to the cell membrane. Using a yeast two-hybrid screen we found that SftA interacts with the conserved cell division protein SepF. Based on extensive genetic analyses and previous data we propose that the septal localization of SftA depends on either SepF or the cell division protein FtsA. Since SftA seems to interfere with the activity of SepF, and since inactivation of SepF mitigates the sensitivity of a ∆sftA mutant for ciprofloxacin, we speculate that SftA might delay septum synthesis when chromosomal DNA is in the vicinity

Prototypage rapide d'un decodeur mpeg-4 optimise sur architectures heterogenes paralleles

- Les solutions Mpeg-4 actuellement développées sont séquentielles et tentent d'intégrer un maximum de fonctionnalités dans un unique logiciel, et sont généralement surdimensionnées en comparaison des services réellement nécessaires. De plus, elles sont difficilement utilisables dans un contexte multiprocesseurs de part leurs importantes tailles de codes et de données, mais également de part l'utilisation sous-optimale du parallélisme de l'architecture. Ce papier présente une application Mpeg-4 distribuée, où la partie système est localisée sur un PC standard, les calculs intensifs de décodage vidéo étant pris en charge par une carte multi-DSP. Nous présentons la méthodologie AVS/SynDEx utilisée pour la création de cette application. AVS/SynDEx autorise une remise à jour simple du décodeur vidéo, mais également le prototypage quasi-automatique sur une plate-forme multi-C6x. Nous définissons également un ordonnancement global permettant l'exécution en parallèle de la partie système et du décodage vidéo

Protein-tyrosine phosphorylation interaction network in Bacillus subtilis reveals new substrates, kinase activators and kinase cross-talk

Signal transduction in eukaryotes is generally transmitted through phosphorylation cascades that involve a complex interplay of transmembrane receptors, protein kinases, phosphatases and their targets. Our previous work indicated that bacterial protein-tyrosine kinases and phosphatases may exhibit similar properties, since they act on many different substrates. To capture the complexity of this phosphorylation-based network, we performed a comprehensive interactome study focused on the protein-tyrosine kinases and phosphatases in the model bacterium Bacillus subtilis. The resulting network identified many potential new substrates of kinases and phosphatases, some of which were experimentally validated. Our study highlighted the role of tyrosine and serine/threonine kinases and phosphatases in DNA metabolism, transcriptional control and cell division. This interaction network reveals significant crosstalk among different classes of kinases. We found that tyrosine kinases can bind to several modulators, transmembrane or cytosolic, consistent with a branching of signaling pathways. Most particularly, we found that the division site regulator MinD can form a complex with the tyrosine kinase PtkA and modulate its activity in vitro. In vivo, it acts as a scaffold protein which anchors the kinase at the cell pole. This network highlighted a role of tyrosine phosphorylation in the spatial regulation of the Z-ring during cytokinesis

Beyond Do Loops: Data Transfer Generation with Convex Array Regions

Abstract. Automatic data transfer generation is a critical step for guided or automatic code generation for accelerators using distributed memories. Although good results have been achieved for loop nests, more complex control ows such as switches or while loops are generally not handled. This paper shows how to leverage the convex array regions abstraction to generate data transfers. The scope of this study ranges from inter-procedural analysis in simple loop nests with function calls, to inter-iteration data reuse optimization and arbitrary control ow in loop bodies. Generated transfers are approximated when an exact solution cannot be found. Array regions are also used to extend redundant load store elimination to array variables. The approach has been successfully applied to GPUs and domain-speci c hardware accelerators

PNeuro: A scalable energy-efficient programmable hardware accelerator for neural networks

Proceedings of a meeting held 19-23 March 2018, Dresden, GermanyInternational audienceArtificial intelligence and especially Machine Learning recently gained a lot of interest from the industry. Indeed, new generation of neural networks built with a large number of successive computing layers enables a large amount of new applications and services implemented from smart sensors to data centers. These Deep Neural Networks (DNN) can interpret signals to recognize objects or situations to drive decision processes. However, their integration into embedded systems remains challenging due to their high computing needs. This paper presents PNeuro, a scalable energy-efficient hardware accelerator for the inference phase of DNN processing chains. Simple programmable processing elements architectured in SIMD clusters perform all the operations needed by DNN (convolutions, pooling, non-linear functions, etc.). An FDSOI 28 nm prototype shows an energy efficiency of 700 GMACS/s/W at 800 MHz. These results open important perspectives regarding the development of smart energy-efficient solutions based on Deep Neural Networks

Interaction of bacterial fatty-acid-displaced regulators with DNA is interrupted by tyrosine phosphorylation in the helix-turn-helix domain

Bacteria possess transcription regulators (of the TetR family) specifically dedicated to repressing genes for cytochrome P450, involved in oxidation of polyunsaturated fatty acids. Interaction of these repressors with operator sequences is disrupted in the presence of fatty acids, and they are therefore known as fatty-acid-displaced regulators. Here, we describe a novel mechanism of inactivating the interaction of these proteins with DNA, illustrated by the example of Bacillus subtilis regulator FatR. FatR was found to interact in a two-hybrid assay with TkmA, an activator of the protein-tyrosine kinase PtkA. We show that FatR is phosphorylated specifically at the residue tyrosine 45 in its helix-turn-helix domain by the kinase PtkA. Structural modelling reveals that the hydroxyl group of tyrosine 45 interacts with DNA, and we show that this phosphorylation reduces FatR DNA binding capacity. Point mutants mimicking phosphorylation of FatR in vivo lead to a strong derepression of the fatR operon, indicating that this regulatory mechanism works independently of derepression by polyunsaturated fatty acids. Tyrosine 45 is a highly conserved residue, and PtkA from B. subtilis can phosphorylate FatR homologues from other bacteria. This indicates that phosphorylation of tyrosine 45 may be a general mechanism of switching off bacterial fatty-acid-displaced regulators