title: A Native Threonine Coordinates Ordered Water to Tune Light-Oxygen-Voltage (LOV) Domain Photocycle Kinetics and Osmotic Stress Signaling in Trichoderma reesei ENVOY.
abstract: Light-oxygen-voltage (LOV) domain-containing proteins function as small light-activated modules capable of imparting blue light control of biological processes. Their small modular nature has made them model proteins for allosteric signal transduction and optogenetic devices. Despite intense research, key aspects of their signal transduction mechanisms and photochemistry remain poorly understood. In particular, ordered water has been identified as a possible key mediator of photocycle kinetics, despite the lack of ordered water in the LOV active site. Herein, we use recent crystal structures of a fungal LOV protein ENVOY to interrogate the role of Thr(101) in recruiting water to the flavin active site where it can function as an intrinsic base to accelerate photocycle kinetics. Kinetic and molecular dynamic simulations confirm a role in solvent recruitment to the active site and identify structural changes that correlate with solvent recruitment. In vivo analysis of T101I indicates a direct role of the Thr(101) position in mediating adaptation to osmotic stress, thereby verifying biological relevance of ordered water in LOV signaling. The combined studies identify position 101 as a mediator of both allostery and photocycle catalysis that can impact organism physiology.
authors.affiliation: From the Department of Chemistry, Southern Methodist University, Dallas, Texas 75275.
authors.forename: Jameela
authors.initials: J
authors.lastname: Lokhandwala
authors.affiliation: the Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, and.
authors.forename: Rafael I
authors.initials: RI
authors.lastname: Silverman Y de la Vega
authors.affiliation: From the Department of Chemistry, Southern Methodist University, Dallas, Texas 75275.
authors.forename: Hilary C
authors.initials: HC
authors.lastname: Hopkins
authors.affiliation: From the Department of Chemistry, Southern Methodist University, Dallas, Texas 75275.
authors.forename: Collin W
authors.initials: CW
authors.lastname: Britton
authors.affiliation: the Department of Health and Environment, Austrian Institute of Technology, Bioresources, 3430 Tulln, Austria.
authors.forename: Aroa
authors.initials: A
authors.lastname: Rodriguez-Iglesias
authors.affiliation: the Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California 95064, and.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bogomolni
authors.affiliation: the Department of Health and Environment, Austrian Institute of Technology, Bioresources, 3430 Tulln, Austria.
authors.forename: Monika
authors.initials: M
authors.lastname: Schmoll
authors.affiliation: From the Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, bzoltowski@smu.edu.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Zoltowski
mesh_terms: D006860:Hydrogen Bonding; D007700:Kinetics; D009997:Osmotic Pressure; D010100:Oxygen / Q000378:metabolism*; D010802:Phylogeny; D015398:Signal Transduction; D013912:Threonine / Q000378:metabolism*; D014242:Trichoderma / Q000145:classification / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D013912:Threonine; D010100:Oxygen
keywords: LOV domain; kinetics; molecular dynamics; optogenetics; osmotic stress; photobiology; structure-function