Andrew Knight

Date on Senior Honors Thesis

5-2016

Document Type

Senior Honors Thesis

Department

Chemistry

Degree Program

College of Arts and Sciences

Author's Keywords

Salamander; Evolution; Pheromone; Proteomics; Plethodontid TIMP-like Protein (PTP); Plethodontid modulating factor (PMF); Plethodontid Receptivity Factor (PRF)

Abstract

Plethodon shermani is a species of lungless salamander that has a complex courtship ritual during which the female straddles the male’s tail. The male then uses a submandibular mental gland to secrete nonvolatile proteinaceous pheromones to increase females’ receptivity to mating. Investigation of the pheromone extract indicated the presence of a protein, termed Plethodontid TIMP-like protein (PTP), with no pheromonelike activity that bears sequence similarity to a group of proteins known as Tissue Inhibitors of Matrix Metalloproteinases (TIMPs). PTP was functionally characterized by measuring its ability to inhibit a range of mouse and human Matrix Metalloproteinases (MMPs). The results of this experiment indicated that PTP is capable of inhibiting at least one human MMP, hMMP-1, a collagenase. Confocal fluorescence microscopy of mental gland cross sections probing for PTP, collagen, and Plethodontid Receptivity Factor (PRF) revealed that PTP is colocalized with pheromones in the mental gland, which helps to explain why PTP is found in the pheromone extract. It is hypothesized that regular PTP secretion during mating acts as a biochemical signal that the mating season is ongoing and that the mental gland should be maintained. Additionally, a recombinant PTP was also expressed in P. pastoris for use in further structural characterization.

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