7a6p

Publication Abstract from PubMed

The primary photochemistry is similar among the flavin-bound sensory domains of LOV (Light-oxygen-voltage) photoreceptors, where upon blue-light illumination a covalent adduct is formed on the microseconds time scale between the flavin chromophore and a strictly conserved cysteine residue. In contrast, the adduct-state decay kinetics vary from seconds to days or longer. The molecular basis for this variation among structurally conserved LOV domains is not fully understood. Here we selected PpSB2-LOV, a fast cycling (taurec 3.5 min, 20 degrees C) short LOV protein from Pseudomonas putida that shares 67% sequence identity with a slow-cycling (taurec 2467 min, 20 degrees C) homologous protein PpSB1-LOV. Based on the crystal structure of the PpSB2-LOV in the dark state reported here, we used a comparative approach, in which we combined structure and sequence information with molecular dynamics (MD) simulations to address the mechanistic basis for the vastly different adduct-state lifetimes in the two homologous proteins. MD simulations pointed towards dynamically distinct structural region, which were subsequently targeted by site-directed mutagenesis of PpSB2-LOV, where we introduced single- and multi-site substitutions exchanging them with the corresponding residues from PpSB1-LOV. Collectively, the data presented identifies key amino acids on the Abeta-Bbeta, Ealpha-Falpha loops, and the Falpha helix, such as E27 and I66, that play a decisive role in determining the adduct-lifetime. Our results additionally suggest a correlation between the solvent-accessibility of the chromophore pocket and adduct-state lifetime. The presented results add to our understanding of LOV signaling, and will have important implications in tuning the signaling behavior (on/off kinetics) of LOV-based optogenetic tools.

Structural determinants underlying the adduct lifetime in the LOV proteins of Pseudomonas putida.,Arinkin V, Granzin J, Krauss U, Jaeger KE, Willbold D, Batra-Safferling R FEBS J. 2021 Feb 23. doi: 10.1111/febs.15785. PMID:33621443^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.