Structural basis of the substrate-specific two-step catalysis of long chain fatty acyl-CoA synthetase dimer.
Long chain fatty acyl-CoA synthetases are responsible for fatty acid degradation as well as physiological regulation of cellular functions via the production of long chain fatty acyl-CoA esters. We report the first crystal structures of long chain fatty acyl-CoA synthetase homodimer (LC-FACS) from Thermus thermophilus HB8 (ttLC-FACS), including complexes with the ATP analogue adenosine 5'-(beta,gamma-imido) triphosphate (AMP-PNP) and myristoyl-AMP. ttLC-FACS is a member of the adenylate forming enzyme superfamily that catalyzes the ATP-dependent acylation of fatty acid in a two-step reaction. The first reaction step was shown to propagate in AMP-PNP complex crystals soaked with myristate solution. Myristoyl-AMP was identified as the intermediate. The AMP-PNP and the myristoyl-AMP complex structures show an identical closed conformation of the small C-terminal domains, whereas the uncomplexed form shows a variety of open conformations. Upon ATP binding, the fatty acid-binding tunnel gated by an aromatic residue opens to the ATP-binding site. The gated fatty acid-binding tunnel appears only to allow one-way movement of the fatty acid during overall catalysis. The protein incorporates a hydrophobic branch from the fatty acid-binding tunnel that is responsible for substrate specificity. Based on these high resolution crystal structures, we propose a unidirectional Bi Uni Uni Bi Ping-Pong mechanism for the two-step acylation by ttLC-FACS.
Hisanaga
Yuko
Y
Structural Biophysics Laboratory, RIKEN Harima Institute at SPring-8, Sayo, Hyogo, Japan.
Ago
Hideo
H
Nakagawa
Noriko
N
Hamada
Keisuke
K
Ida
Koh
K
Yamamoto
Masaki
M
Hori
Tetsuya
T
Arii
Yasuhiro
Y
Sugahara
Mitsuaki
M
Kuramitsu
Seiki
S
Yokoyama
Shigeyuki
S
Miyano
Masashi
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D002384:Catalysis; D020134:Catalytic Domain; D003066:Coenzyme A Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D016963:Thermus thermophilus / Q000201:enzymology / Q000235:genetics
D017931:DNA Primers; D004269:DNA, Bacterial; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D003066:Coenzyme A Ligases