Protein tyrosine phosphatases of Toxoneuron nigriceps bracovirus as potential disrupters of host prothoracic gland function.
The genomic sequence of the bracovirus associated with the wasp Toxoneuron nigriceps (Hymenoptera, Braconidae) (TnBV), an endophagous parasitoid of the tobacco budworm larvae, Heliothis virescens (Lepidoptera, Noctuidae), contains a large gene family coding for protein tyrosine phosphatases (PTPs). Here we report the characterization of cDNAs for two of the viral PTPs isolated by screening a cDNA library from haemocytes of parasitized host larvae. The two encoded proteins show 70% amino acid identity and are expressed in the fat body of parasitized hosts. In addition, one was expressed in inactivated prothoracic glands (PTGs), 24 h after parasitoid oviposition. The rapid block of ecdysteroidogenesis does not appear to be due to inhibition of general protein synthesis, as indirectly indicated by the unaltered S6 kinase activity in the cytosolic extracts of basal PTGs from parasitized host larvae. Rather, TnBV PTP over-expression in inactivated host PTGs suggests that gland function may be affected by the disruption of the phosphorylation balance of key proteins regulating points upstream from the ribosomal S6 phosphorylation in the PTTH signaling cascade.
Dipartimento di Biologia, Difesa e Biotecnologie Agro-Forestali, Università della Basilicata, Potenza, Italy.
Patrizia
P
Falabella
Pasqua
P
Caccialupi
Paola
P
Varricchio
Carla
C
Malva
Francesco
F
Pennacchio
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D005216:Fat Body / Q000502:physiology; D007915:Lepidoptera / Q000469:parasitology* / Q000502:physiology*; D008969:Molecular Sequence Data; D018071:Polydnaviridae / Q000201:enzymology* / Q000235:genetics; D014176:Protein Biosynthesis / Q000502:physiology; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019893:Ribosomal Protein S6 Kinases / Q000502:physiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014863:Wasps / Q000235:genetics / Q000821:virology*
D018076:DNA, Complementary; D012333:RNA, Messenger; D019893:Ribosomal Protein S6 Kinases; D017027:Protein Tyrosine Phosphatases