GBE Diversity and Evolution of Sensor Histidine Kinases in Eukaryotes Samar Kabbara1,†,Anaı¨sHerivaux 1,†, Thomas Duge de Bernonville2, Vincent Courdavault2, Marc Clastre2, Amandine Gastebois1, Marwan Osman3,MonzerHamze3,J.MarkCock4, Pauline Schaap5,andNicolas Papon1,* 1Groupe d’Etude des Interactions Hoˆ te-Pathoge` ne, GEIHP, EA3142, Universite d’Angers, SFR 4208 ICAT, France 2Biomolecules et Biotechnologies Veg etales, BBV, EA2106, Universite Franc¸ois Rabelais de Tours, France 3Laboratoire Microbiologie Sante et Environnement, FacultedeSant e Publique, Universite Libanaise, Tripoli, Lebanon 4Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universite, UPMC Universite Paris 06, CNRS, Roscoff, France 5School of Life Sciences, University of Dundee, United Kingdom †These authors contributed equally to this work. *Corresponding author: E-mail:
[email protected]. Accepted: September 24, 2018 Abstract Histidine kinases (HKs) are primary sensor proteins that act in cell signaling pathways generically referred to as “two- component systems” (TCSs). TCSs are among the most widely distributed transduction systems used by both prokaryotic and eukaryotic organisms to detect and respond to a broad range of environmental cues. The structure and distribution of HK proteins are now well documented in prokaryotes, but information is still fragmentary for eukaryotes. Here, we have taken advantage of recent genomic resources to explore the structural diversity and the phylogenetic distribution of HKs in the prominent eukaryotic supergroups. Searches of the genomes of 67 eukaryotic species spread evenly throughout the phylogenetic tree of life identified 748 predicted HK proteins. Independent phylogenetic analyses of predicted HK proteins were carried out for each of the major eukaryotic supergroups.