Structure and Function of a Luciferase from Gonyaulax Polyedra
Abstract
The structure of a single light-emitting domain from the luciferase of the marine dinoflagellate Lingulodinium Polyedrum has been solved and refined to 1.8 A resolution. The Lingulodinium luciferase (LCF) is a 140 kDa enzyme comprised of three contiguous, repeated luciferase domains, each expressing its own luciferase activity. This LCF has no sequence or structural similarity to that of the bacterial, coelenterate or firefly enzymes. The structure reported here is that of the C-terminal domain D3. The overall structure of the enzyme places it in the family of beta-barrels with a characteristic beta-clam fold at the core. The structure at pH 8.0 reveals that access to the interior of the barrel, and presumably the active site, is blocked by a helix-loop-helix that rests in contact with a small N- terminal subdomain. The pH/rate profile for the D3 domain and the full-length LCF reveal that the enzyme is most active at pH 6.3 and has little activity at pH 8.0. Preliminary molecular dynamics calculations indicate that histidine residues at the interface of the helix-loop-helix and the N-terminal subdomain become charged and initiate a large molecular motion that exposes the active site. Molecular modeling of the luciferin substrate and site-directed mutagenesis in the active site implicate an aspartate residue in the catalytic mechanism.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 2005
- Accession Number
- ADA447531
Entities
People
- Wayne L. Schultz