Solution structure of the transmembrane 2 domain of the human melanocortin-4 receptor in sodium dodecyl sulfate (SDS) micelles and the functional implication of the D90N mutant.
The melanocortin receptors (MCRs) are members of the G protein-coupled receptor (GPCR) 1 superfamily with seven transmembrane (TM) domains. Among them, the melanocortin-4 receptor (MC4R) subtype has been highlighted recently by genetic studies in obese humans. In particular, in a patient with severe early-onset obesity, a novel heterozygous mutation in the MC4R gene was found in an exchange of Asp to Asn in the 90th amino acid residue located in the TM 2 domain (MC4RD90N). Mutations in the MC4R gene are the most frequent monogenic causes of severe obesity and are described as heterozygous with loss of function. We determine solution structures of the TM 2 domain of MC4R (MC4RTM2) and compared secondary structure of Asp90 mutant (MC4RTM2-D90N) in a micelle environment by nuclear magnetic resonance (NMR) spectroscopy. NMR structure shows that MC4RTM2 forms a long α-helix with a kink at Gly98. Interestingly, the structure of MC4RTM2-D90N is similar to that of MC4RTM2 based on data from CD and NMR spectrum. However, the thermal stability and homogeneity of MC4RD90N is quite different from those of MC4R. The structure from molecular modeling suggests that Asp90(2.50) plays a key role in allosteric sodium ion binding. Our data suggest that the sodium ion interaction of Asp90(2.50) in the allosteric pocket of MC4R is essential to its function, explaining the loss of function of the MC4RD90N mutant.
Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Ji-Hye
JH
Yun
Department of Bioinformatics, Korea University, Sejong 136-701, Republic of Korea.
Minsup
M
Kim
Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Kuglae
K
Kim
Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Dongju
D
Lee
Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Youngjin
Y
Jung
Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Daeseok
D
Oh
National Center for Inter-University Research Facilities, Seoul National University, Seoul 151-747, Republic of Korea.
Yoon-Joo
YJ
Ko
Department of Bioinformatics, Korea University, Sejong 136-701, Republic of Korea.
Art E
AE
Cho
Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
Hyun-Soo
HS
Cho
Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea. Electronic address: wlee@spin.yonsei.ac.kr.
Weontae
W
Lee
D000595:Amino Acid Sequence; D001665:Binding Sites; D002942:Circular Dichroism; D006801:Humans; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry* / Q000378:metabolism*; D055550:Protein Stability; D017433:Protein Structure, Secondary; D044105:Receptor, Melanocortin, Type 4 / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D012492:Salts / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012996:Solutions; D040681:Structural Homology, Protein
D007477:Ions; C470072:MC4R protein, human; D008823:Micelles; D050505:Mutant Proteins; D044105:Receptor, Melanocortin, Type 4; D012492:Salts; D012996:Solutions; D012967:Sodium Dodecyl Sulfate; D012964:Sodium
Melanocortin receptor; Nuclear magnetic resonance spectroscopy; Obesity; Sodium allosteric binding; Transmembrane domain