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Vol. 19, Issue 4, 1529-1539, April 2008

This Article Full Text Full Text (PDF) All Versions of this Article: E07-07-0723v1 19/4/1529    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Miller, R. K. Articles by Benian, G. M. PubMed PubMed Citation Articles by Miller, R. K. Articles by Benian, G. M.

UNC-98 and UNC-96 Interact with Paramyosin to Promote Its Incorporation into Thick Filaments of Caenorhabditis elegans

Rachel K. Miller^*,, Hiroshi Qadota^*, Kristina B. Mercer^*, Kim M. Gernert, and Guy M. Benian^*

*Department of Pathology, Graduate Division of Biological and Biomedical Sciences, and BIMCORE (Molecular Graphics), Emory University, Atlanta, GA 30322

Submitted July 29, 2007; Revised January 14, 2008; Accepted January 30, 2008
Monitoring Editor: Thomas Pollard

Mutations in unc-96 or -98 cause reduced motility and a characteristic defect in muscle structure: by polarized light microscopy birefringent needles are found at the ends of muscle cells. Anti-paramyosin stains the needles in unc-96 and -98 mutant muscle. However there is no difference in the overall level of paramyosin in wild-type, unc-96, and -98 animals. Anti-UNC-98 and anti-paramyosin colocalize in the paramyosin accumulations of missense alleles of unc-15 (encodes paramyosin). Anti-UNC-96 and anti-UNC-98 have diffuse localization within muscles of unc-15 null mutants. By immunoblot, in the absence of paramyosin, UNC-98 is diminished, whereas in paramyosin missense mutants, UNC-98 is increased. unc-98 and -15 or unc-96 and -15 interact genetically either as double heterozygotes or as double homozygotes. By yeast two-hybrid assay and ELISAs using purified proteins, UNC-98 interacts with paramyosin residues 31-693, whereas UNC-96 interacts with a separate region of paramyosin, residues 699-798. The importance of surface charge of this 99 residue region for UNC-96 binding was shown. Paramyosin lacking the C-terminal UNC-96 binding region fails to localize throughout A-bands. We propose a model in which UNC-98 and -96 may act as chaperones to promote the incorporation of paramyosin into thick filaments.

Address correspondence to: Guy M. Benian (pathgb{at}emory.edu).

Abbreviations used: MHC, myosin heavy chain; MBP, maltose-binding protein; GFP, green fluorescent protein; ELISA, enzyme-linked immunosorbent assay.