title: Molecular characterization of a novel, developmentally regulated small embryonic chaperone from Caenorhabditis elegans.
abstract: Low molecular weight chaperones inhibit protein aggregation and facilitate refolding of partially denatured polypeptides in cells subjected to physical and chemical stresses. The nematode Caenorhabditis elegans provides a system amenable for investigations on roles for chaperone proteins in normal homeostasis and development. We characterized a C. elegans gene and cDNAs that encode a novel, small embryonic chaperone-like protein (SEC-1) that is composed of 159 amino acids. The central core of SEC-1 (residues 45-126) is approximately 40% identical with a corresponding segment of mammalian Hsp27 and alphaB crystallin. Expression of SEC-1 in Escherichia coli confers thermotolerance on the bacterium. SEC-1 mRNA is evident only in C. elegans oocytes and developing embryos. Translation and accumulation of SEC-1 protein is temporally coupled with a prolonged burst of intense protein synthesis and rapid mitogenesis during early embryogenesis. As the rate of protein synthesis decreases during late embryogenesis, levels of SEC-1 and its cognate mRNA decline precipitously. Induction/deinduction of SEC-1 is precisely regulated by intrinsic developmental factors rather than extrinsic stresses. In vivo injection of C. elegans oocytes with antisense oligonucleotides that complement the 5'-end of SEC-1 mRNA arrests nematode development at an early stage after fertilization. Thus, SEC-1 appears to be adapted to perform essential functions in early embryogenesis.
authors.affiliation: Department of Pediatrics, Atran Laboratories, Albert Einstein College of Medicine, Bronx, New York, 10461, USA.
authors.forename: B
authors.initials: B
authors.lastname: Linder
authors.forename: Z
authors.initials: Z
authors.lastname: Jin
authors.forename: J H
authors.initials: JH
authors.lastname: Freedman
authors.forename: C S
authors.initials: CS
authors.lastname: Rubin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002104:Cadmium / Q000494:pharmacology; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins; D018076:DNA, Complementary; D018507:Gene Expression Regulation, Developmental; D006358:Hot Temperature; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D009626:Terminology as Topic
chemical_list: D029742:Caenorhabditis elegans Proteins; D018076:DNA, Complementary; D018832:Molecular Chaperones; D012333:RNA, Messenger; C102603:sip-1 protein, C elegans; D002104:Cadmium