ABSTRACT
Photorhabdus luminescens is a symbiont of nematodes and a broad-spectrum insect pathogen. The complete genome sequence of strain TT01 is 5,688,987 base pairs (bp) long and contains 4,839 predicted protein-coding genes. Strikingly, it encodes a large number of adhesins, toxins, hemolysins, proteases and lipases, and contains a wide array of antibiotic synthesizing genes. These proteins are likely to play a role in the elimination of competitors, host colonization, invasion and bioconversion of the insect cadaver, making P. luminescens a promising model for the study of symbiosis and host-pathogen interactions. Comparison with the genomes of related bacteria reveals the acquisition of virulence factors by extensive horizontal transfer and provides clues about the evolution of an insect pathogen. Moreover, newly identified insecticidal proteins may be effective alternatives for the control of insect pests.
Subject(s)
Bacterial Toxins/chemistry , Bacterial Toxins/metabolism , Genome, Bacterial , Photorhabdus/chemistry , Photorhabdus/metabolism , Proteome/chemistry , Proteome/metabolism , Sequence Analysis, Protein/methods , Amino Acid Sequence , Animals , Bacterial Toxins/genetics , Gene Expression Regulation, Bacterial/genetics , Molecular Sequence Data , Photorhabdus/genetics , Photorhabdus/pathogenicity , Rhabditoidea/microbiology , Sequence Alignment/methods , Sequence Homology, Amino Acid , Symbiosis/geneticsABSTRACT
A statistical analysis of 9000 flanking sequence tags characterizing transferred DNA (T-DNA) transformants in Arabidopsis sheds new light on T-DNA insertion by illegitimate recombination. T-DNA integration is favoured in plant DNA regions with an A-T-rich content. The formation of a short DNA duplex between the host DNA and the left end of the T-DNA sets the frame for the recombination. The sequence immediately downstream of the plant A-T-rich region is the master element for setting up the DNA duplex, and deletions into the left end of the integrated T-DNA depend on the location of a complementary sequence on the T-DNA. Recombination at the right end of the T-DNA with the host DNA involves another DNA duplex, 2-3 base pairs long, that preferentially includes a G close to the right end of the T-DNA.
