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Disulfide bonding pattern in a structurally constrained family of 7 kDa vertebrate pheromones
Author(s) -
Feldhoff Richard Carlton,
Bowen K E,
Cai J,
Pierce W M,
Houck L D,
Feldhoff P W
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a972-c
Subject(s) - sex pheromone , pheromone , subfamily , gene isoform , chemistry , disulfide bond , vomeronasal organ , courtship , biochemistry , stereochemistry , biology , receptor , genetics , zoology , gene
During courtship, a male P. shermani salamander delivers pheromones from a submandibular mental gland to the female's nares. Following binding of pheromones to receptors in the vomeronasal organ, female receptivity increases. The pheromone mixture consists of two major families, each of which contains multiple isoforms. The 22 kDa family (Plethodontid Receptivity Factor) is related to the IL‐6 family of cytokines, while the 7 kDa family (Plethodontid Modulating Factor; PMF) is related to xenoxins and snake toxins. Recently, we purified and performed peptide mass fingerprinting of 16 PMF isoforms, of which 8 matched our current database of 32 unique DNA sequences. The 7 kDa pheromones have 8 conserved Cys residues (4 disulfide bonds; ~60 residues) with spacing similar to that for xenoxins and snake toxins, but with limited sequence homology. Conditions for the determination of the disulfide bonding pattern were developed for a single purified isoform which resulted in the average reduction and alkylation of 1, 2 or 3 disulfide bonds. Aliquots of each were then subjected to complete digestion with trypsin, chymotrypsin or Glu‐C prior to direct MALDI‐TOF analysis. All of the MS data sets are consistent with a sequential disulfide bonding pattern of 1–2, 3–4, 5–6 and 7–8, with the 3–4 bond being more susceptible to reduction and alkylation than the 1–2 bond. This pattern will dictate a 3‐dimensional structure different from that for xenoxins and snake toxins (1–3, 2–4, 5–6, 7–8) and may represent a subfamily for courtship pheromones or a new family of 8 Cys/7 kDa proteins. Supported in part by NSF Grant # IBN 0110666