Structure and function of the N-terminal domain of Ralstonia eutropha polyhydroxyalkanoate synthase, and the proposed structure and mechanisms of the whole enzyme.
Polyhydroxyalkanoates (PHAs) are natural polyesters synthesized by numerous microorganisms as energy and reducing power storage materials, and have attracted much attention as substitutes for petroleum-based plastics. In an accompanying paper, the authors reported the crystal structure of the C-terminal domain of Ralstonia eutropha PHA synthase (PhaC1). Here, the authors report the 3D reconstructed model of full-length of R. eutropha PhaC1 (RePhaC1F) by small angle X-ray scattering (SAXS) analysis. The catalytic C-terminal domain of RePhaC1 (RePhaC1CD) dimer is located at the center of RePhaC1F, and the N-terminal domain of RePhaC1 (RePhaC1ND) is located opposite the dimerization subdomain of RePhaC1CD, indicating that RePhaC1NDis not directly involved in the enzyme catalysis. The localization studies using RePhaC1F, RePhaC1NDand RePhaC1CDrevealed that RePhaC1NDplays important roles in PHA polymerization by localizing the enzyme to the PHA granules and stabilizing the growing PHA polymer near the active site of RePhaC1CD. The serial truncation study on RePhaC1NDsuggested that the predicted five α-helices (N-α3 to N-α7) are required for proper folding and granule binding function of RePhaC1ND. In addition, the authors also report the SAXS 3D reconstructed model of the RePhaC1F/RePhaMΔCcomplex (RePhaMΔC, PAKKA motif-truncated version of RePhaM). RePhaM forms a complex with RePhaC1 by interacting with RePhaC1NDand activates RePhaC1 by providing a more extensive surface area for interaction with the growing PHA polymer.
School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea.
Yeo-Jin
YJ
Kim
Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), BioProcess Engineering Research Center, Center for Systems and Synthetic Biotechnology, and Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
So Young
SY
Choi
School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea.
Jieun
J
Kim
Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Republic of Korea.
Kyeong Sik
KS
Jin
Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), BioProcess Engineering Research Center, Center for Systems and Synthetic Biotechnology, and Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
Sang Yup
SY
Lee
School of Life Sciences, KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea.
Kyung-Jin
KJ
Kim
D000217:Acyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020118:Cupriavidus necator / Q000201:enzymology*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism; D054813:Polyhydroxyalkanoates / Q000378:metabolism; D000072417:Protein Domains; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
D054813:Polyhydroxyalkanoates; D000217:Acyltransferases; C077225:poly(3-hydroxyalkanoic acid) synthase
3D reconstructed model; Enzyme mechanism; PHA synthase; PhaM; Polyhydroxyalkanoates