A genome-wide screening of the 70 kDa heat shock protein (HSP70) genes in the rotifer Brachionus plicatilis sensu stricto with a characterization of two heat-inducible HSP70 genes

Genomic loss of the HSP70cA gene in the vertebrate lineage

“…All nodes were well resolved with a high posterior probability. The topology of these phylogenetic trees generally supported findings of previous studies (Grewal et al 2022;Yu et al 2021). First, the four lineages were clearly separated, and yeast HSP70s were basal to metazoan HSP70s in each lineage, confirming the ancient separation of the four lineages.…”

“…Their subcellular localization of HSP70 changes depending on cellular conditions (Mattos et al 2022; Mohamad et al 2022; Velazquez and Lindquist 1984), but the organelle-specific isoforms can be clearly distinguished by taking advantage of phylogenetic analyses. Namely, metazoan HSP70s have been robustly classified into four lineages, cytosolic A (HSP70cA), cytosolic B (HSP70cB), endoplasmic reticulum (ER) (HSP70er), and mitochondria (HSP70m), in Bayesian and maximum likelihood frameworks (Schnebert et al 2022; Yu et al 2021), which has been supported by several genome-wide HSP70 screening studies (Grewal et al 2022; Hasnain and Kaneko; Kaneko 2022; Liu et al 2022). It should be noted that the metazoan HSP70 family also contains non-canonical members that often show ~30% or less amino acid identities with above HSP70s [e.g., Homo sapiens HSP70 4L (NP_055093.2); also see Grewal et al (2022)].…”

“…Namely, metazoan HSP70s have been robustly classified into four lineages, cytosolic A (HSP70cA), cytosolic B (HSP70cB), endoplasmic reticulum (ER) (HSP70er), and mitochondria (HSP70m), in Bayesian and maximum likelihood frameworks (Schnebert et al 2022;Yu et al 2021), which has been supported by several genome-wide HSP70 screening studies (Grewal et al 2022;Hasnain and Kaneko ;Kaneko 2022;Liu et al 2022). It should be noted that the metazoan HSP70 family also contains noncanonical members that often show ~30% or less amino acid identities with above HSP70s [e.g., Homo sapiens HSP70 4L (NP_055093.2); also see Grewal et al (2022)]. Considering that E. coli DnaK (WP_023278178.1) and H. sapiens HSP70-1A (NSPA1A, NP_005336.3) share ~50% amino acid identity, these non-canonical HSP70 genes must have diverged very early in their evolutionary history of eukaryotes.…”

“…First, HSP70cAs have been found only from invertebrates including Cnidaria, Priapulida, Mollusca, Rotifera, Annelida, and Arthropoda (Yu et al 2021), suggesting a possible gene loss event during the evolution in the chordate lineage. Second, HSP70cAs have a characteristic serine residue in the ATPase domain with a few exceptions (Drosopoulou et al 2009; Grewal et al 2022; Kourtidis et al 2006; Yu et al 2021), although the function of this residue remains to be elucidated. Third, the HSP70 family members with a relatively constitutive expression pattern, which have been traditionally called the 70 kDa heat shock cognates (HSC70), exclusively belong to the HSP70cB lineage (Yu et al 2021).…”

Hsp70 Gene Family in Sebastiscus marmoratus: The Genome-Wide Identification and Transcriptome Analysis under Thermal Stress

“…As a highly conserved protein, heat shock protein 70 kDa (Hsp70) could protect features in response to intense cellular stress by assisting in their refolding and stabilization [ 1 , 2 ]. By correcting protein folding, Hsps could minimize the aggregation of unnatural proteins and denatured proteins, which have a significant influence on resistance to adverse environmental stresses as a group of molecular chaperones [ 3 , 4 , 5 , 6 ].…”