Self-complementary motifs (SCM) in alpha-crystallin small heat shock proteins.
Small heat shock proteins (sHsp) have been implicated in many cell processes involving the dynamics of protein-protein interactions. Two unusual sequences containing self-complementary motifs (SCM) have been identified within the conserved alpha-crystallin domain of sHsps. When two SCMs are aligned in an anti-parallel direction (N to C and C to N), the charged or polar residues form either salt bridges or hydrogen bonds while the non-polar residues participate in hydrophobic interactions. When aligned in reverse order, the residues of these motifs in alpha-crystallin subunits form either hydrophobic and/or polar interactions. Homology based molecular modeling of the C-terminal domain of alpha-crystallin subunits using the crystal structure of MjHSP16.5 suggests that SCM1 and 2 participate in stabilizing secondary structure and subunit interactions. Also there is overwhelming evidence that these motifs are important in the chaperone-like activity of alpha-crystallin subunits. These sequences are conserved and appear to be characteristic of the entire sHsp superfamily. Similar motifs are also present in the Hsp70 family and the immunoglobulin superfamily.
Farnsworth
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Department of Pharmacology and Physiology, UMD-New Jersey Medical School, Newark, New Jersey 07103, USA. farnswor@umdnj.edu
Singh
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D000595:Amino Acid Sequence; D017124:Conserved Sequence; D003459:Crystallins / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000737:chemistry*; D006801:Humans; D017017:Methanococcus / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D003459:Crystallins; D006360:Heat-Shock Proteins