Structural basis for the hydrolysis of ATP by a nucleotide binding subunit of an amino acid ABC transporter from Thermus thermophilus.
ATP-binding cassette (ABC) transporters are a major family of small molecule transporter proteins, and their deregulation is associated with several diseases, including cancer. Here, we report the crystal structure of the nucleotide binding domain (NBD) of an amino acid ABC transporter from Thermus thermophilus (TTHA1159) in its apo form and as a complex with ADP along with functional studies. TTHA1159 is a putative arginine ABC transporter. The apo-TTHA1159 was crystallized in dimeric form, a hitherto unreported form of an apo NBD. Structural comparison of the apo and ADP-Mg(2+) complexes revealed that Phe14 of TTHA1159 undergoes a significant conformational change to accommodate ADP, and that the bound ADP interacts with the P-loop (Gly40-Thr45). Modeling of ATP-Mg(2+):TTHA1159 complex revealed that Gln86 and Glu164 are involved in water-mediated hydrogen bonding contacts and Asp163 in Mg(2+) ion-mediated hydrogen bonding contacts with the γ-phosphate of ATP, consistent with the findings of other ABC transporters. Mutational studies confirmed the necessity of each of these residues, and a comparison of the apo/ADP Mg(2+):TTHA1159 with its ATP-complex model suggests the likelihood of a key conformational change to the Gln86 side chain for ATP hydrolysis.
Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Chennai 600 025, India.
Seenivasan Karthiga
SK
Devi
Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
Vishnu Priyanka Reddy
VP
Chichili
Department of Bioinformatics, Alagappa University, Karaikudi 630 004, India.
J
J
Jeyakanthan
Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Chennai 600 025, India. Electronic address: dvelmurugan@unom.ac.in.
D
D
Velmurugan
Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore. Electronic address: dbsjayar@nus.edu.sg.
J
J
Sivaraman
D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism*; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites / Q000502:physiology; D006860:Hydrogen Bonding; D006868:Hydrolysis; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D011487:Protein Conformation; D016963:Thermus thermophilus / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D000596:Amino Acids; D001426:Bacterial Proteins; D009711:Nucleotides; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium
ADP; ATP; Crystal structure; TTHA1159; Thermus thermophilus; Transporters