Meeting Abstract
28.6 Wednesday, Jan. 5 Analysis Of Projectin Isoforms And Biomechanics Of Insect Flight Muscles AYME-SOUTHGATE, Agnes*; BEAR, Sean; SCHILDER, Ruud; MARDEN, Jim; TURNER, Larchinee; College of Charleston, Charleston ; College of Charleston, Charleston ; Penn State College of Medicine, State College ; Penn State University, State College ; College of Charleston, Charleston southgatea@cofc.edu
Insect flight muscles are extraordinary in their diversity at the anatomical, physiological and molecular levels. The myofibrillar structure provide the muscle with its contractile properties contributing to muscle stiffness, which is different across insect orders. In derived insects a large part of the flight muscles elasticity is attributed to connecting C-filaments, composed of two large proteins, kettin and projectin. We use a genomic approach to investigate the structure-function relationship for several domains of the projectin protein. The molecular characterization of projectin in basal and derived insects reveals a highly conserved modular organization, including immunoglobulin and fibronectin domains together with a unique PEVK region. We will present the phylogenetic analysis of different projectin domains, pointing to the functional specialization of different segments of the protein, from highly conserved domains involved in anchoring to highly divergent “disordered elastic domains. The unusual amino acid composition of the PEVK segment, as well as its overall lack of conservation will be discussed in light of its proposed role as the elastic segment in the projecin protein. We will present evidence for the expression of distinct PEVK isoforms due to alternative splicing in different muscle types. In all insects tested, from the dragonfly Libellula pulchella to the fruitfly Drosophila melanogaster, the predominant isoform of the flight muscles contains a short PEVK domain. In Libellula pulchella we provide evidence for the correlation between unique combinations of such PEVK isoforms and differences in muscle mechanical properties.
