Project description:Casposons are a group of bacterial and archaeal DNA transposons encoding a specific integrase, termed casposase, which is homologous to the Cas1 enzyme responsible for the integration of new spacers into CRISPR loci. Here, we characterized the sequence motifs recognized by the casposase from a thermophilic archaeon Aciduliprofundum boonei. We identified a stretch of residues, located in the leader region upstream of the actual integration site, whose deletion or mutagenesis impaired the concerted integration reaction. However, deletions of two-thirds of the target site were fully functional. Various single-stranded 6-FAM-labelled oligonucleotides derived from casposon terminal inverted repeats were as efficiently incorporated as duplexes into the target site. This result suggests that, as in the case of spacer insertion by the CRISPR Cas1-Cas2 integrase, casposon integration involves splaying of the casposon termini, with single-stranded ends being the actual substrates. The sequence critical for incorporation was limited to the five terminal residues derived from the 3' end of the casposon. Furthermore, we characterize the casposase from Nitrosopumilus koreensis, a marine member of the phylum Thaumarchaeota, and show that it shares similar properties with the A. boonei enzyme, despite belonging to a different family. These findings further reinforce the mechanistic similarities and evolutionary connection between the casposons and the adaptation module of the CRISPR-Cas systems.
Project description:The green rice leafhopper Nephotettix cincticeps have two mutualistic symbiotic bacteria (Candidatus Sulcia muelleri and Candidatus Nasuia deltocephalinicola) in its symbiont special organ bacteriome and are also infected to rickettsia. In order to determine immune challenge is induced or not in N. cincticeps, we investigated gene expression of Escherichia coli challenged N. cincticeps.
Project description:This study evaluated the transcriptional reprogramming of a susceptible genotype (Pera sweet orange) challenged with the pathogenic bacteria Candidatus Liberibacter americanus (CaLam), using a customized 385K microarray containing about 32,000 unigene transcripts. For the microarray experiment were used symptomatic leaves from two Pera sweet orange plants inoculated with either bark or bud pieces infected with Candidatus Liberibacter americanus and two non-infected control plants.