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BMC Struct Biol. 2009 Oct 24;9:67. doi: 10.1186/1472-6807-9-67.

Structural insights into the substrate tunnel of Saccharomyces cerevisiae carbonic anhydrase Nce103.

Author information

  • 1Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, PR China. ybteng@mail.ustc.edu.cn

Abstract

BACKGROUND:

The carbonic anhydrases (CAs) are involved in inorganic carbon utilization. They have been classified into six evolutionary and structural families: alpha-, beta-, gamma-, delta-, epsilon-, zeta- CAs, with beta-CAs present in higher plants, algae and prokaryotes. The yeast Saccharomyces cerevisiae encodes a single copy of beta-CA Nce103/YNL036W.

RESULTS:

We determined the crystal structure of Nce103 in complex with a substrate analog at 2.04 A resolution. It assembles as a homodimer, with the active site located at the interface between two monomers. At the bottom of the substrate pocket, a zinc ion is coordinated by the three highly conserved residues Cys57, His112 and Cys115 in addition to a water molecule. Residues Asp59, Arg61, Gly111, Leu102, Val80, Phe75 and Phe97 form a tunnel to the bottom of the active site which is occupied by a molecule of the substrate analog acetate. Activity assays of full length and two truncated versions of Nce103 indicated that the N-terminal arm is indispensable.

CONCLUSION:

The quaternary structure of Nce103 resembles the typical plant type beta-CAs of known structure, with an N-terminal arm indispensable for the enzymatic activity. Comparative structure analysis enables us to draw a possible tunnel for the substrate to access the active site which is located at the bottom of a funnel-shaped substrate pocket.

PMID:
19852838
[PubMed - indexed for MEDLINE]
PMCID:
PMC2775743
Free PMC Article

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