title: Drosophila UNC-45 prevents heat-induced aggregation of skeletal muscle myosin and facilitates refolding of citrate synthase.
abstract: UNC-45 belongs to the UCS (UNC-45, CRO1, She4p) domain protein family, whose members interact with various classes of myosin. Here we provide structural and biochemical evidence that Escherichia coli-expressed Drosophila UNC-45 (DUNC-45) maintains the integrity of several substrates during heat-induced stress in vitro. DUNC-45 displays chaperone function in suppressing aggregation of the muscle myosin heavy meromyosin fragment, the myosin S-1 motor domain, alpha-lactalbumin and citrate synthase. Biochemical evidence is supported by electron microscopy, which reveals the first structural evidence that DUNC-45 prevents inter- or intra-molecular aggregates of skeletal muscle heavy meromyosin caused by elevated temperatures. We also demonstrate for the first time that UNC-45 is able to refold a denatured substrate, urea-unfolded citrate synthase. Overall, this in vitro study provides insight into the fate of muscle myosin under stress conditions and suggests that UNC-45 protects and maintains the contractile machinery during in vivo stress.
authors.affiliation: Department of Biology and the Molecular Biology Institute, San Diego State University, San Diego, CA 92182-4614, USA.
authors.forename: Girish C
authors.initials: GC
authors.lastname: Melkani
authors.forename: Chi F
authors.initials: CF
authors.lastname: Lee
authors.forename: Anthony
authors.initials: A
authors.lastname: Cammarato
authors.forename: Sanford I
authors.initials: SI
authors.lastname: Bernstein
mesh_terms: D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D007768:Lactalbumin / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009119:Muscle Contraction; D015879:Myosin Subfragments / Q000378:metabolism*; D017510:Protein Folding; D024744:Skeletal Muscle Myosins / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D018832:Molecular Chaperones; D015879:Myosin Subfragments; C550552:UNC-45 protein, Drosophila; D007768:Lactalbumin; D002950:Citrate (si)-Synthase; D024744:Skeletal Muscle Myosins
references.citation: J Cell Sci. 2002 Nov 1;115(Pt 21):4013-23
references.pmid: 12356907
references.citation: J Mol Biol. 2006 May 5;358(3):635-45
references.pmid: 16546210
references.citation: Science. 2002 Jan 25;295(5555):669-71
references.pmid: 11809970
references.citation: J Biol Chem. 2003 Dec 12;278(50):50293-300
references.pmid: 14506231
references.citation: Trends Biochem Sci. 2004 Mar;29(3):103-6
references.pmid: 15055201
references.citation: J Cell Biol. 2004 Oct 25;167(2):315-25
references.pmid: 15504913
references.citation: Dev Biol. 2007 Aug 1;308(1):133-43
references.pmid: 17586488
references.citation: Nat Cell Biol. 2007 Apr;9(4):379-90
references.pmid: 17369820
references.citation: Dev Dyn. 2002 Aug;224(4):457-60
references.pmid: 12203738
references.citation: Proc Natl Acad Sci U S A. 2008 Jun 10;105(23):8014-9
references.pmid: 18523008
references.citation: J Biochem. 1979 Feb;85(2):457-72
references.pmid: 154513
references.citation: Nature. 1974 Aug 16;250(467):579-80
references.pmid: 4845659
references.citation: Methods Enzymol. 1982;85 Pt B:55-71
references.pmid: 6214692
references.citation: Mol Cell Biol. 2006 Mar;26(5):1722-30
references.pmid: 16478993
references.citation: J Biol Chem. 2008 May 9;283(19):13185-93
references.pmid: 18326487
references.citation: Dev Biol. 1992 Dec;154(2):231-44
references.pmid: 1426637
references.citation: Biochemistry. 1991 Feb 12;30(6):1586-91
references.pmid: 1671555
references.citation: Nature. 1983 Mar 31-Apr 6;302(5907):436-9
references.pmid: 6687627
references.citation: Cell Motil Cytoskeleton. 1999;42(3):163-77
references.pmid: 10098931
references.citation: J Cell Biol. 1998 Nov 30;143(5):1215-25
references.pmid: 9832550
references.citation: FEBS Lett. 2002 Jul 3;522(1-3):59-64
references.pmid: 12095619
references.citation: Proc Natl Acad Sci U S A. 1998 Feb 3;95(3):1004-9
references.pmid: 9448275
references.citation: J Struct Biol. 1990 May;103(3):249-56
references.pmid: 2261309
references.citation: Curr Biol. 2003 Jul 1;13(13):R525-7
references.pmid: 12842031
references.citation: Trends Cell Biol. 2008 Jun;18(6):264-72
references.pmid: 18495480
references.citation: PLoS One. 2008 May 14;3(5):e2137
references.pmid: 18478096
references.citation: Am J Physiol Heart Circ Physiol. 2007 Feb;292(2):H1009-17
references.pmid: 17040975
references.citation: J Cell Biol. 2008 Mar 24;180(6):1163-75
references.pmid: 18347070
references.citation: J Cell Sci. 2000 Jul;113 ( Pt 13):2421-32
references.pmid: 10852821
references.citation: Dev Biol. 2007 Mar 15;303(2):483-92
references.pmid: 17189627
references.citation: J Biol Chem. 2001 May 4;276(18):15117-24
references.pmid: 11134017
references.citation: J Cell Biol. 2007 Apr 23;177(2):205-10
references.pmid: 17438072