title: Diversity of cytosolic HSP70 Heat Shock Protein from decapods and their phylogenetic placement within Arthropoda.
abstract: The 70kDa heat shock proteins (HSP70) are considered the most conserved members of the HSP family. These proteins are primordial to the cell, because of their implications in many cellular pathways (e. g., development, immunity) and also because they minimize the effects of multiple stresses (e. g., temperature, pollutants, salinity, radiations). In the cytosol, two ubiquitous HSP70s with either a constitutive (HSC70) or an inducible (HSP70) expression pattern are found in all metazoan species, encoded by 5 or 6 genes (Drosophila melanogaster or yeast and human respectively). The cytosolic HSP70 protein family is considered a major actor in environmental adaptation, and widely used in ecology as an important biomarker of environmental stress. Nevertheless, the diversity of cytosolic HSP70 remains unclear amongst the Athropoda phylum, especially within decapods. Using 122 new and 311 available sequences, we carried out analyses of the overall cytosolic HSP70 diversity in arthropods (with a focus on decapods) and inferred molecular phylogenies. Overall structural and phylogenetic analyses showed a surprisingly high diversity in cytosolic HSP70 and revealed the existence of several unrecognised groups. All crustacean HSP70 sequences present signature motifs and molecular weights characteristic of non-organellar HSP70, with multiple specific substitutions in the protein sequence. The cytosolic HSP70 family in arthropods appears to be constituted of at least three distinct groups (annotated as A, B and C), which comprise several subdivisions, including both constitutive and inducible forms. Group A is constituted by several classes of Arthropods, while group B and C seem to be specific to Malacostraca and Hexapoda/Chelicerata, respectively. The HSP70 organization appeared much more complex than previously suggested, and far beyond a simple differentiation according to their expression pattern (HSC70 versus HSP70). This study proposes a new classification of cytosolic HSP70 and an evolutionary model of the distinct forms amongst the Arthropoda phylum. The observed differences between HSP70 groups will probably have to be linked to distinct interactions with co-chaperones or other co-factors.
authors.affiliation: Université du Maine, Laboratoire Mer-Molécules-Santé FR-CNRS 3473 IUML, Avenue Olivier Messiaen, 72085 Le Mans, France. Electronic address: stephane.baringou@univ-lemans.fr.
authors.forename: Stephane
authors.initials: S
authors.lastname: Baringou
authors.affiliation: Laboratoire Evolution, Génomes et Spéciation, UPR9034, CNRS, 91198 Gif-sur-Yvette, France; Université Paris, Sud 11, 91405, Orsay, France. Electronic address: jacques-deric.rouault@orange.fr.
authors.forename: Jacques-Deric
authors.initials: JD
authors.lastname: Rouault
authors.affiliation: LABOCEA-CNRS, 29280 Plouzané, France. Electronic address: mhmkoken@gmail.com.
authors.forename: Marcel
authors.initials: M
authors.lastname: Koken
authors.affiliation: Université du Maine, Laboratoire Mer-Molécules-Santé FR-CNRS 3473 IUML, Avenue Olivier Messiaen, 72085 Le Mans, France. Electronic address: yann.hardivillier@univ-lemans.fr.
authors.forename: Yann
authors.initials: Y
authors.lastname: Hardivillier
authors.affiliation: Department of Wildlife and Fisheries, Texas A&M University, Old Heep Building 110E, TAMU College Station, TX 77843-2258, USA. Electronic address: lhurtado@tamu.edu.
authors.forename: Luis
authors.initials: L
authors.lastname: Hurtado
authors.affiliation: Université du Maine, Laboratoire Mer-Molécules-Santé FR-CNRS 3473 IUML, Avenue Olivier Messiaen, 72085 Le Mans, France. Electronic address: vincent.leignel@univ-lemans.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Leignel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003600:Cytosol / Q000378:metabolism*; D030562:Databases, Protein; D033364:Decapoda / Q000235:genetics*; D014644:Genetic Variation; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D007438:Introns / Q000235:genetics; D010802:Phylogeny; D017433:Protein Structure, Secondary
chemical_list: D018840:HSP70 Heat-Shock Proteins
keywords: Arthropods; Crustacea; HSP70 family; Molecular evolution; Phylogeny