Interaction of the N-terminus of chicken skeletal essential light chain 1 with F-actin.
Skeletal myosin has two isoforms of the essential light chain (ELC), called LC1 and LC3, which differ only in their N-terminal amino acid sequence. The LC1 has 41 additional residues containing seven pairs of Ala-Pro, which form an elongated structure, and two pairs of lysines located near the N-terminus. When myosin subfragment-1 (S1) binds to actin, these lysines may interact with the C-terminus of actin and be responsible for the isoform specific properties of myosin. Here we employ cross-linking to identify the LC1 residues that are in contact with actin. S1 was reconstituted with various LC1 mutants and reacted with the zero-length cross-linker 1-ethyl-3-[3-dimethyl-aminopropyl]-carbodiimide (EDC). Cross-linking occurred only when actin was in molar excess over S1. Wild-type LC1 could be cross-linked through the terminal alpha-NH2 group, as well as via the two pairs of lysines. In a mutant ELC, where the lysines were deleted but two arginines were introduced near the N-terminus, the light chain could still be cross-linked via the terminal alpha-NH2 group. When the charge was reduced in the N-terminal region while retaining the Ala-Pro rich region, the mutant could not be cross-linked. These results suggest that as long as the N-terminus contains charged residues and an Ala-Pro rich extension, the binding between LC1 and actin can occur.
Andreev
O A
OA
Department of Biochemistry and Molecular Biology, University of North Texas, Fort Worth 76107, USA.
Saraswat
L D
LD
Lowey
S
S
Slaughter
C
C
Borejdo
J
J
D000199:Actins / Q000378:metabolism* / Q000502:physiology; D000409:Alanine / Q000235:genetics / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000502:physiology; D002234:Carbodiimides / Q000378:metabolism; D002645:Chickens; D003432:Cross-Linking Reagents / Q000378:metabolism; D018698:Glutamic Acid / Q000235:genetics / Q000502:physiology; D008239:Lysine / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D011392:Proline / Q000235:genetics / Q000502:physiology; D017384:Sequence Deletion
D000199:Actins; D002234:Carbodiimides; D003432:Cross-Linking Reagents; D018994:Myosin Light Chains; D010446:Peptide Fragments; C076659:myosin light chain I; C074139:1-ethyl-3-(3-dimethylaminoethyl)carbodiimide; D001224:Aspartic Acid; D018698:Glutamic Acid; D011392:Proline; D008239:Lysine; D000409:Alanine