Migration of Type III Secretion System Transcriptional Regulators Links Gene Expression to Secretion.

Many plant-pathogenic bacteria of considerable economic importance rely on type III secretion systems (T3SSs) of the Hrc-Hrp 1 family to subvert their plant hosts. T3SS gene expression is regulated through the HrpG and HrpV proteins, while secretion is controlled by the gatekeeper HrpJ. A link between the two mechanisms was so far unknown.

A Career on Both Sides of the Atlantic: Memoirs of a Molecular Plant Pathologist.

This article recounts the experiences that shaped my career as a molecular plant pathologist. It focuses primarily on technical and conceptual developments in molecular phytobacteriology, shares some personal highlights and untold stories that impacted my professional development, and describes the early years of agricultural biotechnology. Writing this article required reflection on events occurring over several decades that were punctuated by a mid-career relocation across the Atlantic.

A phage tail-derived element with wide distribution among both prokaryotic domains: a comparative genomic and phylogenetic study.

Prophage sequences became an integral part of bacterial genomes as a consequence of coevolution, encoding fitness or virulence factors. Such roles have been attributed to phage-derived elements identified in several Gram-negative species: The type VI secretion system (T6SS), the R- and F-type pyocins, and the newly discovered Serratia entomophila antifeeding prophage (Afp), and the Photorhabdus luminescens virulence cassette (PVC). In this study, we provide evidence that remarkably conserved gene clusters, homologous to Afp/PVC, are not restricted to Gram-negative bacteria but are widespread throughout all prokaryotes including the Archaea.

Pipelines for New Chemicals: a strategy to create new value chains and stimulate innovation-based economic revival in Southern European countries.

Countries of Southern Europe are currently suffering from severe socio-economic pain resulting from high debt levels and austerity measures which constrain investment in innovation-based recovery strategies that are essential for entry into a long-term sustainable period of increasing employment and wealth creation. Young university-educated people are particularly innovative, and hence vital to the development of such strategies, but employment opportunities are poor and many are forced to seek employment that neither profits from their training nor satisfies their justified career expectations, or to emigrate. They are the 'lost generation'.

Comparative genomics of multiple strains of Pseudomonas cannabina pv. alisalensis, a potential model pathogen of both monocots and dicots.

Comparative genomics of closely related pathogens that differ in host range can provide insights into mechanisms of host-pathogen interactions and host adaptation. Furthermore, sequencing of multiple strains with the same host range reveals information concerning pathogen diversity and the molecular basis of virulence. Here we present a comparative analysis of draft genome sequences for four strains of Pseudomonas cannabina pathovar alisalensis (Pcal), which is pathogenic on a range of monocotyledonous and dicotyledonous plants.

Phytobacterial type III effectors HopX1, HopAB1 and HopF2 enhance sense-post-transcriptional gene silencing independently of plant R gene-effector recognition.

Plant- and animal-pathogenic bacteria deploy a variable arsenal of type III effector proteins (T3EP) to manipulate host defense. Specific biochemical functions and molecular or subcellular targets have been demonstrated or proposed for a growing number of T3EP but remain unknown for the majority of them. Here, we show that transient expression of genes coding certain bacterial T3EP (HopAB1, HopX1, and HopF2), which did not elicit hypersensitive response (HR) in transgenic green fluorescent protein (GFP) Nicotiana benthamiana 16C line, enhanced the sense post-transcriptional gene silencing (S-PTGS) triggered by agrodelivery of a GFP-expressing cassette and the silencing enhancement could be blocked by two well-known viral silencing suppressors.

In silico analysis reveals multiple putative type VI secretion systems and effector proteins in Pseudomonas syringae pathovars.

Type VI secretion systems (T6SS) of Gram-negative bacteria form injectisomes that have the potential to translocate effector proteins into eukaryotic host cells. In silico analysis of the genomes in six Pseudomonas syringae pathovars revealed that P. syringae pv.

Distribution of the putative type VI secretion system core genes in Klebsiella spp.

The type VI secretion system (t6ss) is a recently characterized secretion system which appears to be involved in bacterial pathogenesis as a potential nano-syringe for the translocation of effector proteins into the eukaryotic host cell cytoplasm. Until now no evidence was provided for the presence of t6ss in the genomes of the sequenced representatives of Klebsiella spp., including the human opportunistic pathogen Klebsiella pneumoniae.

Playing the "Harp": evolution of our understanding of hrp/hrc genes.

With the advent of recombinant DNA techniques, the field of molecular plant pathology witnessed dramatic shifts in the 1970s and 1980s. The new and conventional methodologies of bacterial molecular genetics put bacteria center stage. The discovery in the mid-1980s of the hrp/hrc gene cluster and the subsequent demonstration that it encodes a type III secretion system (T3SS) common to Gram negative bacterial phytopathogens, animal pathogens, and plant symbionts was a landmark in molecular plant pathology.

Metabolic engineering of the complete pathway leading to heterologous biosynthesis of various flavonoids and stilbenoids in Saccharomyces cerevisiae.

Chemical or biological synthesis of plant secondary metabolites has attracted increasing interest due to their proven or assumed beneficial properties and health promoting effects. Resveratrol, a stilbenoid, naringenin, a flavanone, genistein, an isoflavone, and the flavonols kaempferol and quercetin have been shown to possess high nutritional and agricultural value. Four metabolically engineered yeast strains harboring plasmids with heterologous genes for enzymes involved in the biosynthesis of these compounds from phenylalanine have been constructed.

Engineered polyamine catabolism preinduces tolerance of tobacco to bacteria and oomycetes.

Polyamine oxidase (PAO) catalyzes the oxidative catabolism of spermidine and spermine, generating hydrogen peroxide. In wild-type tobacco (Nicotiana tabacum 'Xanthi') plants, infection by the compatible pathogen Pseudomonas syringae pv tabaci resulted in increased PAO gene and corresponding PAO enzyme activities; polyamine homeostasis was maintained by induction of the arginine decarboxylase pathway and spermine was excreted into the apoplast, where it was oxidized by the enhanced apoplastic PAO, resulting in higher hydrogen peroxide accumulation. Moreover, plants overexpressing PAO showed preinduced disease tolerance against the biotrophic bacterium P.

Biotechnology of flavonoids and other phenylpropanoid-derived natural products. Part II: Reconstruction of multienzyme pathways in plants and microbes.

Plant natural products derived from phenylalanine and the phenylpropanoid pathways are impressive in their chemical diversity and are the result of plant evolution, which has selected for the acquisition of large repertoires of pigments, structural and defensive compounds, all derived from a phenylpropanoid backbone via the plant-specific phenylpropanoid pathway. These compounds are important in plant growth, development and responses to environmental stresses and thus can have large impacts on agricultural productivity. While plant-based medicines containing phenylpropanoid-derived active components have long been used by humans, the benefits of specific flavonoids and other phenylpropanoid-derived compounds to human health and their potential for long-term health benefits have only been recognized more recently.

Biotechnology of flavonoids and other phenylpropanoid-derived natural products. Part I: Chemical diversity, impacts on plant biology and human health.

Plant natural products derived from phenylalanine and the phenylpropanoid pathway are impressive in their chemical diversity and are the result of plant evolution, which has selected for the acquisition of large repertoires of pigments, structural and defensive compounds, all derived from a phenylpropanoid backbone via the plant-specific phenylpropanoid pathway. These compounds are important in plant growth, development and responses to environmental stresses and thus can have large impacts on agricultural productivity. While plant-based medicines containing phenylpropanoid-derived active components have long been used by humans, the benefits of specific flavonoids and other phenylpropanoid-derived compounds to human health and their potential for long-term health benefits have been only recognized more recently.

Type III protein translocase: HrcN is a peripheral ATPase that is activated by oligomerization.

Type III protein secretion (TTS) is catalyzed by translocases that span both membranes of Gram-negative bacteria. A hydrophilic TTS component homologous to F1/V1-ATPases is ubiquitous and essential for secretion. We show that hrcN encodes the putative TTS ATPase of Pseudomonas syringae pathovar phaseolicola and that HrcN is a peripheral protein that assembles in clusters at the membrane.

In vitro freezing in microtitre plates applied to tobacco plants transformed with the inaZ gene of Pseudomonas syringae.

High throughput assays have been developed to measure the ice nucleation activity of transgenic tobacco, Nicotiana tabacum L. cv. Petit Havana SR1 plants expressing the ice nucleation gene, inaZ, from Pseudomonas syringae at a young seedling stage, as well as in leaf tissue.

Molecular determinants required for the avirulence function of AvrPphB in bean and other plants.

The avirulence gene avrPphB from Pseudomonas syringae pv. phaseolicola determines incompatibility, manifested as a hypersensitive reaction (HR), on bean cultivars carrying the R3 resistance gene and also confers avirulence on other plants. The AvrPphB protein carries an embedded consensus myristoylation motif and is cleaved in bacteria and certain plants to yield fragments of about 6 and 28 kDa.