Structure of Desulfitobacterium hafniense PylSc, a pyrrolysyl-tRNA synthetase |
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Authors: | Lee Marianne M Jiang Ruisheng Jain Rinku Larue Ross C Krzycki Joseph Chan Michael K |
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Institution: | a The Ohio State Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA b The Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA c Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA d Department of Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA e Department of Chemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA |
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Abstract: | Pyrrolysine, the 22nd genetically-encoded amino acid, is charged onto its specific tRNA by PylS, a pyrrolysyl-tRNA synthetase. While PylS is found as a single protein in certain archaeal methanogens, in the Gram-positive bacterium Desulfitobacterium hafniense, PylS is divided into two separate proteins, PylSn and PylSc, corresponding to the N-terminal and C-terminal domains of the single PylS protein found in methanogens. Previous crystallographic studies have provided the structure of a truncated C-terminal portion of the archaeal Methanosarcina mazei PylS associated with catalysis. Here, we report the apo 2.1 Å resolution structure of the intact D. hafniense PylSc protein and compare it to structures of the C-terminal truncated PylS from methanogenic species. In PylSc, the hydrophobic pocket binding the ring of pyrrolysine is more constrained than in the archaeal enzyme; other structural differences are also apparent. |
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Keywords: | Pyrrolysine PylS Pyrrolysyl-tRNA synthetase |
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