HFIP-induced structures and assemblies of the peptides from the transmembrane domain 4 of membrane protein Nramp1.
Membrane protein Nramp1 (natural resistance-associated macrophage protein 1) is a pH-dependent divalent metal cation transporter that regulates macrophage activation in infectious and autoimmune diseases. A naturally occurring glycine to aspartic acid substitution at position 169 (G169D) within the transmembrane domain 4 (TM4) of Nramp1 makes mice susceptible to Leishmania donovani, Salmonella typhimurium, and Mycobacterium bovis. Here we present a structural and self-assembling study on two synthetic 24-residue peptides, corresponding to TM4 of mouse Nramp1 and its G169D mutant, respectively, in 1,1,1,3,3,3-hexafluoroisopropanol-d(2) (HFIP-d(2)) aqueous solution by nuclear magnetic resonance (NMR) spectroscopy. The results show that amphipathic alpha-helical structures are formed from residue Ile173 to Tyr187 for the wild-type peptide and from Trp168 to Tyr187 for the G169D mutant, respectively. The segment of the N-terminus from Leu167 to Leu172 is poorly structured for the wild-type peptide, whereas it is well defined for the G169D mutant. Both peptides aggregate to form a tetramer and the monomeric peptides in peptide bundles are structurally and orientationally similar. The intermolecular interactions in assemblies could be stronger in the C-terminal regions related to residues Phe180-Leu184 than those in the central helical segments for both peptides. The G169D mutation may change the size of the opening on the termini of assembly.
Xue
Rong
R
Key Laboratory for Supramolecular Structure and Materials of Ministry of Education, Jilin University, Changchun, People's Republic of China.
Wang
Shuo
S
Wang
Chunyu
C
Zhu
Tao
T
Li
Fei
F
Sun
Hongzhe
H
D000595:Amino Acid Sequence; D027682:Cation Transport Proteins / Q000737:chemistry* / Q000235:genetics; D002942:Circular Dichroism; D004058:Diffusion; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry*; D020005:Propanols / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry; D000099173:Natural Resistance-associated Macrophage Protein 1; D006845:Hydrocarbons, Fluorinated
D027682:Cation Transport Proteins; D008565:Membrane Proteins; D010455:Peptides; D020005:Propanols; D012996:Solutions; D014867:Water; D000099173:Natural Resistance-associated Macrophage Protein 1; C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated