3FGC

Crystal Structure of the Bacterial Luciferase:Flavin Complex Reveals the Basis of Intersubunit Communication

Summary for 3FGC

• Entry DOI: 10.2210/pdb3fgc/pdb
• Related: 1BRL 1LUC
• Descriptor: Alkanal monooxygenase alpha chain, Alkanal monooxygenase beta chain, FLAVIN MONONUCLEOTIDE, ... (6 entities in total)
• Functional Keywords: fmn bacterial luciferase mobile loop, flavoprotein, fmn, luminescence, monooxygenase, oxidoreductase, photoprotein
• Biological source: Vibrio harveyi; More
• Total number of polymer chains: 4
• Total formula weight: 157489.07

Authors

Campbell, Z.T.,Weichsel, A.,Montfort, W.R.,Baldwin, T.O. (deposition date: 2008-12-05, release date: 2009-05-26, Last modification date: 2023-09-06)

Primary citation

Campbell, Z.T.,Weichsel, A.,Montfort, W.R.,Baldwin, T.O.
Crystal structure of the bacterial luciferase/flavin complex provides insight into the function of the beta subunit.
Biochemistry, 48:6085-6094, 2009

PubMed Abstract: Bacterial luciferase from Vibrio harveyi is a heterodimer composed of a catalytic alpha subunit and a homologous but noncatalytic beta subunit. Despite decades of enzymological investigation, structural evidence defining the active center has been elusive. We report here the crystal structure of V. harveyi luciferase bound to flavin mononucleotide (FMN) at 2.3 A. The isoalloxazine ring is coordinated by an unusual cis-Ala-Ala peptide bond. The reactive sulfhydryl group of Cys106 projects toward position C-4a, the site of flavin oxygenation. This structure also provides the first data specifying the conformations of a mobile loop that is crystallographically disordered in both prior crystal structures [(1995) Biochemistry 34, 6581-6586; (1996) J. Biol. Chem. 271, 21956 21968]. This loop appears to be a boundary between solvent and the active center. Within this portion of the protein, a single contact was observed between Phe272 of the alpha subunit, not seen in the previous structures, and Tyr151 of the beta subunit. Substitutions at position 151 on the beta subunit caused reductions in activity and total quantum yield. Several of these mutants were found to have decreased affinity for reduced flavin mononucleotide (FMNH(2)). These findings partially address the long-standing question of how the beta subunit stabilizes the active conformation of the alpha subunit, thereby participating in the catalytic mechanism.

PubMed: 19435287
DOI: 10.1021/bi900003t

Experimental method

X-RAY DIFFRACTION (2.3 Å)