Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
Differences of the Active Site Structure as Revealed by Sequence Analysis of Slow and Fast Bacterial Luciferases
Bacterial luciferase is a heterodimer that catalyzes the oxidation of reduced flavin (FMNH2) and aliphatic aldehyde yielding light emission. We have analyzed sequences of α- and β-subunits for 20 bacterial luciferases. Analysis revealed that luciferase sequences could be divided into two groups based upon highly conserved amino acid residues in 29 positions (Fig.1, A). What is more important that found clades that correspond to the experimentally proven fact of "slow" and "fast" decay luciferases (Valkova et al., 1999) and correlate with the ecological niche of bacteria. The critical residues of the α-subunit are located in the active site (8), in the vicinity of the active site (5) and on the α/β-interface (7). The analysis of active site structures revealed significant differences in flavin stabilization pattern: fast luciferases contain Ile6 and Phe8 and slow luciferases contain Phe6 and Leu8, that might prove the existence of alternative realization of the mechanism (Fig.1, B); fast luciferases contain Met74 and Val106 and slow luciferases contain Ala74 and Cys106, which probably stabilize isoalloxazine ring by interaction with different nitrogen atoms (Fig.1, C). Conserved regions of α/β--subunit are mostly located near the α/β-interface. A phylogenetic tree for 18-162 amino acid subsequence of β-subunit (residues located on α/β-interface and close to it) forms the same pattern as a phylogenetic tree for whole α--subunit, which could indicate that both interfaces evolved together.
The work was supported by RFBR grant No. 14-34-50215-mol_nr.
Valkova, N., Szittner, R., & Meighen, E. A. (1999). Control of luminescence decay and flavin binding by the LuxA carboxyl-terminal regions in chimeric bacterial luciferases. Biochemistry, 38(42), 13820-13828.
Anna A. Deeva1
1Laboratory of Bioluminescent Biotechnology