Unc-45 mutations in Caenorhabditis elegans implicate a CRO1/She4p-like domain in myosin assembly

José M. Barral, Christopher C. Bauer, Irving Ortiz, Henry F. Epstein

Research output: Contribution to journalArticle

104 Citations (Scopus)

Abstract

The Caenorhabditis elegans unc-45 locus has been proposed to encode a protein machine for myosin assembly. The UNC-45 protein is predicted to contain an NH2-terminal domain with three tetratricopeptide repeat motifs, a unique central region, and a COOH-terminal domain homologous to CRO1 and She4p. CRO1 and She4p are fungal proteins required for the segregation of other molecules in budding, endocytosis, and septation. Three mutations that lead to temperature-sensitive (ts) alleles have been localized to conserved residues within the CRO1/She4p-like domain, and two lethal alleles were found to result from stop codon mutations in the central region that would prevent translation of the COOH-terminal domain. Electron microscopy shows that thick filament accumulation in vivo is decreased by ~50% in the CB286 ts mutant grown at the restrictive temperature. The thick filaments that assemble have abnormal structure. Immunofluorescence and immunoelectron microscopy show that myosins A and B are scrambled, in contrast to their assembly into distinct regions at the permissive temperature and in wild type. This abnormal structure correlates with the high degree of instability of the filaments in vitro as reflected by their extremely low yields and shortened lengths upon isolation. These results implicate the UNC-45 CRO1/She4p-like region in the assembly of myosin isoforms in C. elegans and suggest a possible common mechanism for the function of this UCS (UNC-45/CRO1/She4p) protein family.

Original languageEnglish (US)
Pages (from-to)1215-1225
Number of pages11
JournalJournal of Cell Biology
Volume143
Issue number5
DOIs
StatePublished - Nov 30 1998
Externally publishedYes

Fingerprint

Caenorhabditis elegans
Myosins
Mutation
Temperature
Nonmuscle Myosin Type IIB
Nonmuscle Myosin Type IIA
Lethal Genes
Proteins
Fungal Proteins
Immunoelectron Microscopy
Terminator Codon
Endocytosis
Fluorescence Microscopy
Electron Microscopy
Protein Isoforms
Alleles

Keywords

  • Biosynthesis
  • Caenorhabditis elegans
  • Chaperone
  • Muscle
  • Myosin

ASJC Scopus subject areas

  • Cell Biology

Cite this

Unc-45 mutations in Caenorhabditis elegans implicate a CRO1/She4p-like domain in myosin assembly. / Barral, José M.; Bauer, Christopher C.; Ortiz, Irving; Epstein, Henry F.

In: Journal of Cell Biology, Vol. 143, No. 5, 30.11.1998, p. 1215-1225.

Research output: Contribution to journalArticle

Barral, José M. ; Bauer, Christopher C. ; Ortiz, Irving ; Epstein, Henry F. / Unc-45 mutations in Caenorhabditis elegans implicate a CRO1/She4p-like domain in myosin assembly. In: Journal of Cell Biology. 1998 ; Vol. 143, No. 5. pp. 1215-1225.
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