Fragments from actin binding protein (ABP-280; filamin) insert into reconstituted lipid layers.
Previous computer analyses suggested two possible lipid binding sites, residues 49-71 and 131-155, of the primary amino acid sequence on ABP-280 (filamin), which could facilitate membrane attachment/insertion. We expressed these regions as fusion proteins with schistosomal GST and investigated their interaction with mixtures of zwitterionic (dimyristoyl-l-alpha-phosphatidylcholine, DMPC) and anionic (dimyristoyl-l-alpha-phosphatidylglycerol, DMPG) phospholipids in reconstituted lipid bilayers by differential scanning calorimetry (DSC). Using vesicles of mixed DMPC/DMPG with increasing fusion protein concentrations, we established in calorimetric assays a decrease of the main chain transition enthalpy, DeltaH, and a shift in chain melting temperature. This is indicative of the insertion of these fragments into the hydrophobic region of lipid membranes. We confirmed these findings by the film balance technique using lipid monolayers (DMPG). The binding judged from both methods was of moderate affinity.
Goldmann
W H
WH
Department of Surgery, Children's Hospital, Boston, Massachusetts, USA. goldmann_w@hub.tch.harvard.edu
Teodoridis
J M
JM
Sharma
C P
CP
Hu
B
B
Isenberg
G
G
D000595:Amino Acid Sequence; D001483:Base Sequence; D018821:CD18 Antigens / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D003001:Cloning, Molecular; D003285:Contractile Proteins / Q000737:chemistry*; D064448:Filamins; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D008840:Microfilament Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D011510:Proteolipids / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013816:Thermodynamics
D018821:CD18 Antigens; D003285:Contractile Proteins; D064448:Filamins; D008051:Lipid Bilayers; D008840:Microfilament Proteins; D010446:Peptide Fragments; D010743:Phospholipids; D011510:Proteolipids; D011993:Recombinant Fusion Proteins; C020485:proteoliposomes