The chemosensory appendage proteome of Amblyomma americanum (Acari: Ixodidae) reveals putative odorant-binding and other chemoreception-related proteins.
Proteomic analyses were done on 2 chemosensory appendages of the lone star tick, Amblyomma americanum. Proteins in the fore tarsi, which contain the olfactory Haller's organ, and in the palps, that include gustatory sensilla, were compared with proteins in the third tarsi. Also, male and female ticks were compared. Proteins were identified by sequence similarity to known proteins, and by 3-dimensional homology modeling. Proteomic data were also compared with organ-specific transcriptomes from the tick Rhipicephalus microplus. The fore tarsi express a lipocalin not found in the third tarsi or palps. The fore tarsi and palps abundantly express 2 proteins, which are similar to insect odorant-binding proteins (OBPs). Compared with insect OBPs, the tick OBP-like sequences lacked the cysteine absent in C-minus OBPs, and 1 tick OBP-like sequence had additional cysteines that were similar to C-plus OBPs. Four proteins similar to the antibiotic protein microplusin were found: 2 exclusively expressed in the fore tarsi and 1 exclusively expressed in the palps. These proteins lack the microplusin copper-binding site, but they are modeled to have a significant internal cavity, potentially a ligand-binding site. Proteins similar to the dust mite allergens Der p7 and Der f 7 were found differentially expressed in female fore tarsi. A protein exclusively expressed in the fore tarsi has similarities to Neto, which is known to be involved in clustering of ionotropic glutamate receptors. These results constitute the first report of OBP-like protein sequences in ticks and point to several research avenues on tick chemosensory reception.
Department of Biology, University of Texas at San Antonio, San Antonio, TX, 78249, USA.|Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX, 78229, USA.
Robert
R
Renthal
Department of Biology, University of Texas at San Antonio, San Antonio, TX, 78249, USA.
Leena
L
Manghnani
Department of Biology, University of Texas at San Antonio, San Antonio, TX, 78249, USA.
Sandra
S
Bernal
RCMI Protein Biomarkers Core, University of Texas at San Antonio, San Antonio, TX, 78249, USA.
Yanyan
Y
Qu
RCMI Protein Biomarkers Core, University of Texas at San Antonio, San Antonio, TX, 78249, USA.|Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, 78249, USA.
Wendell P
WP
Griffith
USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory, Veterinary Pest Genomics Center, Kerrville, TX, 78029, USA.
Kim
K
Lohmeyer
USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory, Veterinary Pest Genomics Center, Kerrville, TX, 78029, USA.
Felix D
FD
Guerrero
Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.
Lígia M F
LMF
Borges
USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory, Veterinary Pest Genomics Center, Kerrville, TX, 78029, USA.
Adalberto
A
Pérez de León
D000818:Animals; D002628:Chemoreceptor Cells / Q000378:metabolism*; D005260:Female; D026863:Ixodidae / Q000378:metabolism*; D054834:Lipocalins / Q000378:metabolism; D008297:Male; D020543:Proteome; D018035:Receptors, Odorant / Q000378:metabolism*
D054834:Lipocalins; D020543:Proteome; D018035:Receptors, Odorant
3-dimensional homology modeling; Haller's organ; dust mite allergen; lipocalin; microplusin; odorant-binding protein