November 5, 2004
Isolation and characterization of a new gene from the black
encoding a protein found in egg case silk
Dr. Craig Vierra
University of the Pacific
Abstract: Spiders produce multiple types of silk that
exhibit diverse mechanical properties and biological functions.
Most molecular studies of spider silk have focused on fibroins
from dragline silk and capture silk, two important silk types
involved in the survival of the spider. In our studies we have
focused on the characterization of egg case silk, a third silk
fiber produced by the black widow spider, Latrodectus hesperus.
A main component of egg case silk is a 100-kDa protein doublet,
which is embedded in the silk filament. Using peptide sequences
obtained from MALDI tandem TOF (time-of-flight) mass spectrometry,
we have used reverse genetics to isolate one of the genes corresponding
to the 100-kDa species of the protein doublet. Based upon the
solubility characteristics of the protein, we have named the product
soluble-matrix protein-1 (SMP-1). The expression pattern of smp-1
is largely restricted to the tubuliform gland, with lower levels
detected in the major and minor ampullate glands. The significance
of SMP-1 with respect to egg case function, as well as other silk
types, will be discussed.