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

• Type of Material: Article
• Authors: Ge Xiong, Emory University; Hiroshi Qadota, Emory University; Kristina B. Mercer, Emory University; Lee Anne McGaha, Emory University; Andres F. Oberhauser, University of Texas Medical Branch; Guy Benian, Emory University
• Language: English
• Date: 2009-03-06
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2009 Elsevier Ltd. All rights reserved.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.jmb.2009.01.016
• Title of Journal or Parent Work: Journal of Molecular Biology
• ISSN: 0022-2836
• Volume: 386
• Issue: 4
• Start Page: 976
• End Page: 988
• Grant/Funding Information: Financial support was provided by National Institute of Arthritis & Musculoskeletal & Skin Diseases / National Institutes of Health grant AR-051466.
• Keywords: SARCOPLASMIC-RETICULUM; SKELETAL-MUSCLE; C. elegans; Life Sciences & Biomedicine; GENE; MYOPATHY; INTEGRIN ADHESION COMPLEXES; SEQUENCE; FHL; muscle; CTD phosphatase; THICK FILAMENTS; Biochemistry & Molecular Biology; Science & Technology; DOMAINS; BODY-WALL MUSCLE; obscurin; TITIN KINASE
• Research Categories: Health Sciences, Pathology; Chemistry, Biochemistry; Biology, Molecular

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.