A diatom gene regulating nitric-oxide signaling and susceptibility to diatom-derived aldehydes.
Diatoms are unicellular phytoplankton accounting for approximately 40% of global marine primary productivity [1], yet the molecular mechanisms underlying their ecological success are largely unexplored. We use a functional-genomics approach in the marine diatom Phaeodactylum tricornutum to characterize a novel protein belonging to the widely conserved YqeH subfamily [2] of GTP-binding proteins thought to play a role in ribosome biogenesis [3], sporulation [4], and nitric oxide (NO) generation [5]. Transgenic diatoms overexpressing this gene, designated PtNOA, displayed higher NO production, reduced growth, impaired photosynthetic efficiency, and a reduced ability to adhere to surfaces. A fused YFP-PtNOA protein was plastid localized, distinguishing it from a mitochondria-localized plant ortholog. PtNOA was upregulated in response to the diatom-derived unsaturated aldehyde 2E,4E/Z-decadienal (DD), a molecule previously shown to regulate intercellular signaling, stress surveillance [6], and defense against grazers [7]. Overexpressing cell lines were hypersensitive to sublethal levels of this aldehyde, manifested by altered expression of superoxide dismutase and metacaspases, key components of stress and death pathways [8, 9]. NOA-like sequences were found in diverse oceanic regions, suggesting that a novel NO-based system operates in diatoms and may be widespread in phytoplankton, providing a biological context for NO in the upper ocean [10].
Vardi
Assaf
A
Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, NJ 08901, USA. vardi@marine.rutgers.edu <vardi@marine.rutgers.edu>
Bidle
Kay D
KD
Kwityn
Clifford
C
Hirsh
Donald J
DJ
Thompson
Stephanie M
SM
Callow
James A
JA
Falkowski
Paul
P
Bowler
Chris
C
D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology*; D002448:Cell Adhesion; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D017377:Diatoms / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D018869:Heat-Shock Response; D009569:Nitric Oxide / Q000378:metabolism*; D010788:Photosynthesis; D015398:Signal Transduction
D000447:Aldehydes; C057349:2,4-decadienal; D009569:Nitric Oxide; D019204:GTP-Binding Proteins