Discovery and molecular characteristic analysis of the type I phosphodiesterase genes from Riemerella anatipestifer

A positive clone identified by blue/white selection in the expression DNA library of CH-1 strain of Riemerella anatipestifer (RA) serotype 1 was screened by in situ hybridization using anti-RA rabbit sera. After five rounds of immunoscreening, in vivo excision of a positive phage plague, restriction enzyme digestion analysis and sequencing, an insert sequence of 4434bp was obtained. BLASTN, BLASTP and ORF Finder provided by the American National Center for Biotechnology Information (NCBI) and FASTA provided by the European Molecular Biology Laboratory (EMBL) were applied to the overall bioinformatics analysis of one of the sequence's three open reading frames, denominated ORF1689. The result displayed that the complete ORF contains 1689bp and encodes 562 amino acids. The molecular weight is 59.5 kD and the theoretical pI is 5.82. A ribosome binding site (RBS) was found in the front of the initiator. The gene contains a conserved domain of phosphodiest. And the amino acid sequence deduced from ORF displayed homologies of 49.283%, 38.716%, 38.693% and 38.313% to those from Caulobacter sp. K31, Sphingomonas sp., Sphingopyxis alaskensis and Novosphingobium aromaticivorans, so the gene is a new Type I phosphodiesterase genes. The research result will provide basic theory and experimental data for clarifying the biological function of Type I phosphodiesterase genes and the physiological characteristics and pathologic mechanism of RA.