Identification of amino acid residues that direct differential ligand selectivity of mammalian and nonmammalian V1a type receptors for arginine vasopressin and vasotocin. Insights into molecular coevolution of V1a type receptors and their ligands.
Arginine vasotocin (VT) is the ortholog in all nonmammalian vertebrates of arginine vasopressin (AVP) in mammals. We have previously cloned an amphibian V1atype vasotocin receptor (VT1R) that exhibited higher sensitivity for VT than AVP, while the mammalian V1a type receptor (V1aR) responded better to AVP than VT. In the present study, we identified the amino acid residues that confer differential ligand selectivity for AVP and VT between rat V1aR and bullfrog VT1R (bfVT1R). A chimeric rat V1aR having transmembrane domain (TMD) VI to the carboxyl-terminal tail (C-tail) of bfVT1R showed a reverse ligand preference for AVP and VT, whereas a chimeric VT1R with TMD VI to the C-tail of rat V1aR showed a great increase in sensitivity for AVP. A single mutation (Ile(315(6.53)) to Thr) in TMD VI of V1aR increased the sensitivity for VT, while a single mutation (Phe(313(6.51)) to Tyr or Pro(334(7.33)) to Thr) reduced sensitivity toward AVP. Interestingly the triple mutation (Phe(313(6.51)) to Tyr, Ile(6.53) to Thr, and Pro(7.33) to Thr) of V1aR increased sensitivity to VT but greatly reduced sensitivity to AVP, behaving like bfVT1R. Further, like V1aR, a double mutant (Tyr(306(6.51)) to Phe and Thr(327(7.33)) to Pro) of bfVT1R showed an increased sensitivity to AVP. These results suggest that Phe/Tyr(6.51), Ile/Thr(6.53), and Pro/Thr(7.33) are responsible for the differential ligand selectivity between rat V1aR and bfVT1R. This information regarding the molecular interaction of VT/AVP with their receptors may have important implications for the development of novel AVP analogs.
Acharjee
Sujata
S
Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea.
Do-Rego
Jean-Luc
JL
Oh
D Y
DY
Oh
Da Young
da Y
Ahn
Ryun Sup
RS
Choe
Han
H
Vaudry
Hubert
H
Kim
Kyungjin
K
Seong
Jae Young
JY
Kwon
Hyuk Bang
HB
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D001665:Binding Sites; D015870:Gene Expression; D016762:Genes, fos; D006801:Humans; D007532:Isoleucine; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010649:Phenylalanine; D011392:Proline; D011401:Promoter Regions, Genetic / Q000235:genetics; D011892:Rana catesbeiana; D051381:Rats; D017483:Receptors, Vasopressin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013912:Threonine; D014162:Transfection; D014443:Tyrosine; D014668:Vasotocin / Q000378:metabolism*
D000596:Amino Acids; D017483:Receptors, Vasopressin; D011993:Recombinant Fusion Proteins; C034862:vasotocin receptor; D007532:Isoleucine; D001127:Arginine Vasopressin; D013912:Threonine; D014443:Tyrosine; D010649:Phenylalanine; D011392:Proline; D014668:Vasotocin