The Brown Algal Virus EsV-1 Particle Contains a Putative Hybrid Histidine Kinase

AbstractThe Ectocarpus siliculosus virus, EsV-1, occurs worldwide in all populations of the filamentous marine brown alga E. siliculosus. We have screened an expression library of EsV-1 restriction fragments and identified a DNA clone with the potential to code for a 52-kDa histidine protein kinase. The derived amino acid sequence includes all homology boxes diagnostic for histidine protein kinases and, in addition, amino acid motifs that are commonly found in response regulators of bacterial two-component signal transduction proteins. Thus, the novel viral protein can be classified as a hybrid histidine protein kinase of a type that has previously been detected in fungi, slime molds, and plants. By using purified antibodies, we found that the protein with its potential kinase activity is located on the outer shell of viral particles. This is the first report on a two-component regulator-like protein in viruses and could provide the basis for speculations with regard to the evolution of EsV-1 and related viruses

Transmembrane domain length of viral K+ channels is a signal for mitochondria targeting

K+ channels operate in the plasma membrane and in membranes of organelles including mitochondria. The mechanisms and topogenic information for their differential synthesis and targeting is unknown. This article describes 2 similar viral K+ channels that are differentially sorted; one protein (Kesv) is imported by the Tom complex into the mitochondria, the other (Kcv) to the plasma membrane. By creating chimeras we discovered that mitochondrial sorting of Kesv depends on a hierarchical combination of N- and C-terminal signals. Crucial is the length of the second transmembrane domain; extending its C terminus by \u3e2 hydrophobic amino acids redirects Kesv from the mitochondrial to the plasma membrane. Activity of Kesv in the plasma membrane is detected electrically or by yeast rescue assays only after this shift in sorting. Hence only minor structural alterations in a transmembrane domain are sufficient to switch sorting of a K+ channel between the plasma membrane and mitochondria

Diversity and Evolution of Sensor Histidine Kinases in Eukaryotes

Histidine kinases (HKs) are primary sensor proteins that act in cell signaling pathways generically referred to as "two component systems" (TCSs). TCSs are among the most widely distributed transduction systems used by both prokaryotic and eukaryotic organisms to detect and respond to a broad range of environmental cues. The structure and distribution of HK proteins are now well documented in prokaryotes but information is still fragmentary for eukaryotes. Here, we have taken advantage of recent genomic resources to explore the structural diversity and the phylogenetic distribution of HKs in the prominent eukaryotic supergroups. Searches of the genomes of 67 eukaryotic species spread evenly throughout the phylogenetic tree of life identified 748 predicted HK proteins. Independent phylogenetic analyses of predicted HK proteins were carried out for each of the major eukaryotic supergroups. This allowed most of the compiled sequences to be categorised into previously described HK groups. Beyond the phylogenetic analysis of eukaryotic HKs, this study revealed some interesting findings: (i) characterisation of some previously undescribed eukaryotic HK groups with predicted functions putatively related to physiological traits; (ii) discovery of HK groups that were previously believed to be restricted to a single kingdom in additional supergroups and (iii) indications that some evolutionary paths have led to the appearance, transfer, duplication, and loss of HK genes in some phylogenetic lineages. This study provides an unprecedented overview of the structure and distribution of HKs in the Eukaryota and represents a first step towards deciphering the evolution of TCS signaling in living organisms

The genome of the brown alga contains a series of viral DNA pieces, suggesting an ancient association with large dsDNA viruses-0

Ould have evolved mainly through genome regression as shown by the loss of the OBP ORFs (B, C, D, E). In addition, the giant microbe has probably transferred its genome to the host genome (F) and evolved to give rise to the phaeoviruses (G) and polydnaviruses (H). It is likely that horizontal gene transfer (HGT) occurred between the different organisms present in the primitive eukaryote (A, F). For example, the herpesvirus OBP might have been acquired from the NCLDV ancestor. In the case of the phaeoviruses, the viral integrated fragments could serve as templates for the production of new virions through rearrangement, recombination and mutation (I).<p><b>Copyright information:</b></p><p>Taken from "The genome of the brown alga contains a series of viral DNA pieces, suggesting an ancient association with large dsDNA viruses"</p><p>http://www.biomedcentral.com/1471-2148/8/110</p><p>BMC Evolutionary Biology 2008;8():110-110.</p><p>Published online 12 Apr 2008</p><p>PMCID:PMC2373305.</p><p></p

Coevolution of aah: A dps-Like Gene with the Host Bacterium Revealed by Comparative Genomic Analysis

A protein named AAH was isolated from the bacterium Microbacterium arborescens SE14, a gut commensal of the lepidopteran larvae. It showed not only a high sequence similarity to Dps-like proteins (DNA-binding proteins from starved cell) but also reversible hydrolase activity. A comparative genomic analysis was performed to gain more insights into its evolution. The GC profile of the aah gene indicated that it was evolved from a low GC ancestor. Its stop codon usage was also different from the general pattern of Actinobacterial genomes. The phylogeny of dps-like proteins showed strong correlation with the phylogeny of host bacteria. A conserved genomic synteny was identified in some taxonomically related Actinobacteria, suggesting that the ancestor genes had incorporated into the genome before the divergence of Micrococcineae from other families. The aah gene had evolved new function but still retained the typical dodecameric structure

The genome of the brown alga contains a series of viral DNA pieces, suggesting an ancient association with large dsDNA viruses-1

Ould have evolved mainly through genome regression as shown by the loss of the OBP ORFs (B, C, D, E). In addition, the giant microbe has probably transferred its genome to the host genome (F) and evolved to give rise to the phaeoviruses (G) and polydnaviruses (H). It is likely that horizontal gene transfer (HGT) occurred between the different organisms present in the primitive eukaryote (A, F). For example, the herpesvirus OBP might have been acquired from the NCLDV ancestor. In the case of the phaeoviruses, the viral integrated fragments could serve as templates for the production of new virions through rearrangement, recombination and mutation (I).<p><b>Copyright information:</b></p><p>Taken from "The genome of the brown alga contains a series of viral DNA pieces, suggesting an ancient association with large dsDNA viruses"</p><p>http://www.biomedcentral.com/1471-2148/8/110</p><p>BMC Evolutionary Biology 2008;8():110-110.</p><p>Published online 12 Apr 2008</p><p>PMCID:PMC2373305.</p><p></p

Sympathetic nerve repulsion inhibited by designer molecules in vitro and role in experimental arthritis

Aims: In rheumatoid arthritis and collagen type II arthritis (CIA), sympathetic nerve fibers get lost in inflamed tissue. The process is probably induced by nerve repellent factors like semaphorin 3F (SEMA3F). Repulsion of sympathetic nerve fibers in inflamed tissue has proinflammatory effects due to the loss of anti-inflammatory neurotransmitters. We hypothesized that design molecules like antibodies and specific peptides that inhibit nerve fiber repulsion can ameliorate CIA. Materials and methods: Two blocking antibodies were used and four blocking peptides were generated using the phage display technique with the targets of SEMA3F and plexin-A2. All blocking molecules were tested in vitro using a sympathetic neurite outgrowth assay. CIA was induced by collagen type II in mice. Key findings: In the neurite outgrowth assay, the two antibodies against plexin-A2 and neuropilin-2 as well as the four blocking peptides - two SEMA3F analogous peptides (WLFQRDPGDR, QATVKWLFQRDPGDRR) and two plexin A2 analogous peptides (DSSDQFSFDYELEQN, DSSIQFFSFEKDKERI) - were able to block sympathetic nerve fiber repulsion in vitro (at 150-600 nmol/1). Administration of the two antibodies prophylactically on day 4 after immunization did not change clinical CIA. Similarly, using the top candidate antibody to plexin-A2 after CIA onset (mild score of 4 points, maximum = 52 points), did not ameliorate CIA. The tested blocking peptides were not recovered in peripheral blood after i.v. and i.p. administration. Significance: While designer molecules blocked nerve fiber repulsion in vitro, therapeutic administration in vivo did not change CIA. Possible strategies to overcome negative effects demonstrated in vivo are discussed. (C) 2016 Elsevier Inc. All rights reserved