Sequencing and functional characterization of a Latrodectus geometricus defensin, Lg-defensin

<p>Defensins are small, cysteine-rich, immune related proteins described to be the most widespread family of invertebrate antimicrobial peptides. Presently, there is limited information regarding spider defensins. In this study, a new defensin peptide was described in <em>Latrodectus geometricus, </em>Lg-defensin. The full open reading frame was resolved using RACE and <em>de novo</em> assembly, followed by a bioinformatical analysis and phylogenetic alignment to determine conserved sequence patterns and structural similarities to other defensins. Next, the functionality of Lg-defensin was determined using <em>in vitro </em>RNA interference to assess what impact silencing had on the spider’s ability to control a gram-positive and gram-negative bacterial infection, whose level was determined via qPCR analysis. Results indicated Lg-defensin to be a highly conserved defensin with similar structure and sequence patterns to other related taxa. Additionally, Lg-defensin was found to have higher antibacterial activity towards the gram-positive bacteria in contrast to its effect on gram-negative bacteria. This is the first report regarding the completed characterization of a defensin peptide in <em>L. geometricus </em>and provides a basis for future research regarding Lg-defensin and its clinically relevant capabilities. </p>

Name thesis:degree_name

Master of Science - Biology

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2022

Author dc:creator

• Thompson, Jacklyn Victoria

Contributors dc:contributor

• Dr. Dennis Gravatt
• Dr. Lindsay Porter
• Dr. Zeljko Radulovic

• Antimicrobial Peptides
• Defensins
• RNA-interference
• Latrodectus
• RT-qPCR
• Spiders
• Molecular Biology

Repository record dc:identifier

https://scholarworks.sfasu.edu/etds/477

OAI identifier oai:identifier

oai:scholarworks.sfasu.edu:etds-1511