A LIM-9 (FHL) / SCPL-1 (SCP) Complex Interacts with the C-terminal Protein Kinase Regions of UNC-89 (Obscurin) in Caenorhabditis elegans Muscle

Ge Xiong, Hiroshi Qadota, Kristina B. Mercer, Lee Anne McGaha, Andres F. Oberhauser, Guy M. Benian

    Research output: Contribution to journalArticlepeer-review

    30 Scopus citations

    Abstract

    The C. elegans gene unc-89 encodes a set of mostly giant polypeptides (up to 900 kDa) that contain multiple immunoglobulin (Ig) and fibronectin type 3 (Fn3), a triplet of SH3-DH-PH, and two protein kinase domains. The loss of function mutant phenotype and localization of antibodies to UNC-89 proteins indicate that the function of UNC-89 is to help organize sarcomeric A-bands, especially M-lines. Recently, we reported that each of the protein kinase domains interacts with SCPL-1, which contains a CTD-type protein phosphatase domain. Here, we report that SCPL-1 interacts with LIM-9 (FHL), a protein that we first discovered as an interactor of UNC-97 (PINCH) and UNC-96, components of an M-line costamere in nematode muscle. We show that LIM-9 can interact with UNC-89 through its first kinase domain and a portion of unique sequence lying between the two kinase domains. All the interactions were confirmed by biochemical methods. A yeast three-hybrid assay demonstrates a ternary complex between the two protein kinase regions and SCPL-1. Evidence that the UNC-89/SCPL-1 interaction occurs in vivo was provided by showing that over-expression of SCPL-1 results in disorganization of UNC-89 at M-lines. We suggest two structural models for the interactions of SCPL-1 and LIM-9 with UNC-89 at the M-line.

    Original languageEnglish (US)
    Pages (from-to)976-988
    Number of pages13
    JournalJournal of Molecular Biology
    Volume386
    Issue number4
    DOIs
    StatePublished - Mar 6 2009

    Keywords

    • C. elegans
    • CTD phosphatase
    • FHL
    • muscle
    • obscurin

    ASJC Scopus subject areas

    • Biophysics
    • Structural Biology
    • Molecular Biology

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