Time filter

Source Type

Lefevre C.T.,Aix - Marseille University | Trubitsyn D.,University of Nevada, Las Vegas | Abreu F.,Federal University of Rio de Janeiro | Kolinko S.,Ludwig Maximilians University of Munich | And 11 more authors.
Environmental Microbiology | Year: 2013

Magnetotactic bacteria (MTB) represent a group of diverse motile prokaryotes that biomineralize magnetosomes, the organelles responsible for magnetotaxis. Magnetosomes consist of intracellular, membrane-bounded, tens-of-nanometre-sized crystals of the magnetic minerals magnetite (Fe3O4) or greigite (Fe3S4) and are usually organized as a chain within the cell acting like a compass needle. Most information regarding the biomineralization processes involved in magnetosome formation comes from studies involving Alphaproteobacteria species which biomineralize cuboctahedral and elongated prismatic crystals of magnetite. Many magnetosome genes, the mam genes, identified in these organisms are conserved in all known MTB. Here we present a comparative genomic analysis of magnetotactic Deltaproteobacteria that synthesize bullet-shaped crystals of magnetite and/or greigite. We show that in addition to mam genes, there is a conserved set of genes, designated mad genes, specific to the magnetotactic Deltaproteobacteria, some also being present in CandidatusMagnetobacterium bavaricum of the Nitrospirae phylum, but absent in the magnetotactic Alphaproteobacteria. Our results suggest that the number of genes associated with magnetotaxis in magnetotactic Deltaproteobacteria is larger than previously thought. We also demonstrate that the minimum set of mam genes necessary for magnetosome formation in Magnetospirillum is also conserved in magnetite-producing, magnetotactic Deltaproteobacteria. Some putative novel functions of mad genes are discussed. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

Clark M.S.,Natural Environment Research Council | Denekamp N.Y.,Israel Oceanographic And Limnological Research | Thorne M.A.S.,Natural Environment Research Council | Reinhardt R.,Max Planck Institute for Molecular Genetics | And 7 more authors.
PLoS ONE | Year: 2012

Background: Several organisms display dormancy and developmental arrest at embryonic stages. Long-term survival in the dormant form is usually associated with desiccation, orthodox plant seeds and Artemia cysts being well documented examples. Several aquatic invertebrates display dormancy during embryonic development and survive for tens or even hundreds of years in a hydrated form, raising the question of whether survival in the non-desiccated form of embryonic development depends on pathways similar to those occurring in desiccation tolerant forms. Methodology/Principal Findings: To address this question, Illumina short read sequencing was used to generate transcription profiles from the resting and amictic eggs of an aquatic invertebrate, the rotifer, Brachionus plicatilis. These two types of egg have very different life histories, with the dormant or diapausing resting eggs, the result of the sexual cycle and amictic eggs, the non-dormant products of the asexual cycle. Significant transcriptional differences were found between the two types of egg, with amictic eggs rich in genes involved in the morphological development into a juvenile rotifer. In contrast, representatives of classical "stress" proteins: a small heat shock protein, ferritin and Late Embryogenesis Abundant (LEA) proteins were identified in resting eggs. More importantly however, was the identification of transcripts for messenger ribonucleoprotein particles which stabilise RNA. These inhibit translation and provide a valuable source of useful RNAs which can be rapidly activated on the exit from dormancy. Apoptotic genes were also present. Although apoptosis is inconsistent with maintenance of prolonged dormancy, an altered apoptotic pathway has been proposed for Artemia, and this may be the case with the rotifer. Conclusions: These data represent the first transcriptional profiling of molecular processes associated with dormancy in a non-desiccated form and indicate important similarities in the molecular pathways activated in resting eggs compared with desiccated dormant forms, specifically plant seeds and Artemia. © 2012 Clark et al.

Wohlbrand L.,Carl von Ossietzky University | Jacob J.H.,Max Planck Institute for Marine Microbiology | Jacob J.H.,Al al-Bayt University | Kube M.,Max Planck Institute for Molecular Genetics | And 10 more authors.
Environmental Microbiology | Year: 2013

Among the dominant deltaproteobacterial sulfate-reducing bacteria (SRB), members of the genus Desulfobacula are not only present in (hydrocarbon-rich) marine sediments, but occur also frequently in the anoxic water bodies encountered in marine upwelling areas. Here, we present the 5.2Mbp genome of Desulfobacula toluolicaTol2, which is the first of an aromatic compound-degrading, marine SRB. The genome has apparently been shaped by viral attacks (e.g. CRISPRs) and its high plasticity is reflected by 163 detected genes related to transposases and integrases, a total of 494 paralogous genes and 24 group II introns. Prediction of the catabolic network of strain Tol2 was refined by differential proteome and metabolite analysis of substrate-adapted cells. Toluene and p-cresol are degraded by separate suites of specific enzymes for initial arylsuccinate formation via addition to fumarate (p-cresol-specific enzyme HbsA represents a new phylogenetic branch) as well as for subsequent modified β-oxidation of arylsuccinates to the central intermediate benzoyl-CoA. Proteogenomic evidence suggests specific electron transfer (EtfAB) and membrane proteins to channel electrons from dehydrogenation of both arylsuccinates directly to the membrane redox pool. In contrast to the known anaerobic degradation pathways in other bacteria, strain Tol2 deaminates phenylalanine non-oxidatively to cinnamate by phenylalanine ammonia-lyase and subsequently forms phenylacetate (both metabolites identified in 13C-labelling experiments). Benzoate degradation involves CoA activation, reductive dearomatization by a class II benzoyl-CoA reductase and hydrolytic ring cleavage as found in the obligate anaerobe Geobacter metallireducensGS-15. The catabolic sub-proteomes displayed high substrate specificity, reflecting the genomically predicted complex and fine-tuned regulatory network of strain Tol2. Despite the genetic equipment for a TCA cycle, proteomic evidence supports complete oxidation of acetyl-CoA to CO2 via the Wood-Ljungdahl pathway. Strain Tol2 possesses transmembrane redox complexes similar to that of other Desulfobacteraceae members. The multiple heterodisulfide reductase-like proteins (more than described for Desulfobacterium autotrophicumHRM2) may constitute a multifaceted cytoplasmic electron transfer network. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Mo D.,University of Munster | Raabe C.A.,University of Munster | Reinhardt R.,Max Planck Genome Center Cologne | Brosius J.,University of Munster | Rozhdestvensky T.S.,University of Munster
Genome Biology and Evolution | Year: 2013

The evolution of new genes can ensue through either gene duplication and the neofunctionalization of one of the copies or the formation of a de novo gene from hitherto nonfunctional, neutrally evolving intergenic or intronic genomic sequences. Only very rarely are entire genes created de novo. Mostly, nonfunctional sequences are coopted as novel parts of existing genes, such as in the process of exonizationwhereby introns become exonsthrough changesinsplicing. Here,wereport acasein which anovel nonprotein coding RNA evolved by intron-sequence recruitment into its structure. cDNAs derived from rat brain small RNAs, revealed a novel small nucleolar RNA (snoRNA) originating from one of the Snord115 copies in the rat Prader-Willi syndrome locus. We suggest that a singlepoint substitution in the Snord115 region led to the expression of a longer snoRNA variant, designated as L-Snord115. Cell culture and footprinting experiments confirmed that a single nucleotide substitution at Snord115 position 67 destabilized the kink-turn motif within the canonical snoRNA, while distal intronic sequences provided an alternate D-box region. The exapted sequence displays putative base pairing to 28S rRNA and mRNA targets. © The Author(s) 2013. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Kleemann J.,Max Planck Institute for Plant Breeding Research | Rincon-Rivera L.J.,Max Planck Institute for Plant Breeding Research | Takahara H.,Max Planck Institute for Plant Breeding Research | Takahara H.,Ishikawa Prefectural University | And 10 more authors.
PLoS Pathogens | Year: 2012

Phytopathogens secrete effector proteins to manipulate their hosts for effective colonization. Hemibiotrophic fungi must maintain host viability during initial biotrophic growth and elicit host death for subsequent necrotrophic growth. To identify effectors mediating these opposing processes, we deeply sequenced the transcriptome of Colletotrichum higginsianum infecting Arabidopsis. Most effector genes are host-induced and expressed in consecutive waves associated with pathogenic transitions, indicating distinct effector suites are deployed at each stage. Using fluorescent protein tagging and transmission electron microscopy-immunogold labelling, we found effectors localised to stage-specific compartments at the host-pathogen interface. In particular, we show effectors are focally secreted from appressorial penetration pores before host invasion, revealing new levels of functional complexity for this fungal organ. Furthermore, we demonstrate that antagonistic effectors either induce or suppress plant cell death. Based on these results we conclude that hemibiotrophy in Colletotrichum is orchestrated through the coordinated expression of antagonistic effectors supporting either cell viability or cell death. © 2012 Kleemann et al.

Discover hidden collaborations