title: Characterisation of a plancitoxin-1-like DNase II gene in Trichinella spiralis.
abstract: BACKGROUND
  Deoxyribonuclease II (DNase II) is a well-known acidic endonuclease that catalyses the degradation of DNA into oligonucleotides. Only one or a few genes encoding DNase II have been observed in the genomes of many species. 125 DNase II-like protein family genes were predicted in the Trichinella spiralis (T. spiralis) genome; however, none have been confirmed. DNase II is a monomeric nuclease that contains two copies of a variant HKD motif in the N- and C-termini. Of these 125 genes, only plancitoxin-1 (1095 bp, GenBank accession no. XM_003370715.1) contains the HKD motif in its C-terminus domain.
  
  
  RESULTS
  In this study, we cloned and characterised the plancitoxin-1 gene. However, the sequences of plancitoxin-1 cloned from T. spiralis were shorter than the predicted sequences in GenBank. Intriguingly, there were two HKD motifs in the N- and C-termini in the cloned sequences. Therefore, the gene with shorter sequences was named after plancitoxin-1-like (Ts-Pt, 885 bp) and has been deposited in GenBank under accession number KF984291. The recombinant protein (rTs-Pt) was expressed in a prokaryotic expression system and purified by nickel affinity chromatography. Western blot analysis showed that rTs-Pt was recognised by serum from T. spiralis-infected mice; the anti-rTs-Pt serum recognised crude antigens but not ES antigens. The Ts-Pt gene was examined at all T. spiralis developmental stages by real-time quantitative PCR. Immunolocalisation analysis showed that Ts-Pt was distributed throughout newborn larvae (NBL), the tegument of adults (Ad) and muscle larvae (ML). As demonstrated by DNase zymography, the expressed proteins displayed cation-independent DNase activity. rTs-Pt had a narrow optimum pH range in slightly acidic conditions (pH 4 and pH 5), and its optimum temperature was 25°C, 30°C, and 37°C.
  
  
  CONCLUSIONS
  This study indicated that Ts-Pt was classified as a somatic protein in different T. spiralis developmental stages, and demonstrated for the first time that an expressed DNase II protein from T. spiralis had nuclease activity.
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Chengshui
authors.initials: C
authors.lastname: Liao
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, People's Republic of China.
authors.forename: Mingyuan
authors.initials: M
authors.lastname: Liu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Xue
authors.initials: X
authors.lastname: Bai
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Pan
authors.initials: P
authors.lastname: Liu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Xuelin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Li
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Tang
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: He
authors.initials: H
authors.lastname: Gao
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Xidong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China; National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People's Republic of China.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Pascal
authors.initials: P
authors.lastname: Boireau
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, People's Republic of China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017160:Trichinella spiralis / Q000201:enzymology / Q000235:genetics
chemical_list: D015801:Helminth Proteins; D011994:Recombinant Proteins; D004706:Endodeoxyribonucleases; C019329:deoxyribonuclease II