Probing the Catalytic Charge-Relay System in Alanine Racemase with Genetically Encoded Histidine Mimetics. Academic Article uri icon

abstract

  • Histidine is a unique amino acid with an imidazole side chain in which both of the nitrogen atoms are capable of serving as a proton donor and proton acceptor in hydrogen bonding interactions. In order to probe the functional role of histidine involved in hydrogen bonding networks, fine-tuning the hydrogen bonding potential of the imidazole side chain is required but not feasible through traditional mutagenesis methods. Here, we show that two close mimetics of histidine, 3-methyl-histidine and thiazole alanine, can be genetically encoded using engineered pyrrolysine incorporation machinery. Replacement of the three histidine residues predicted to be involved in an extended charge-relay system in alanine racemase with 3-methyl-histidine or thiazole alanine shows a dramatic loss in the enzyme's catalytic efficiency, implying the role of this extended charge-relay system in activating the active site residue Y265, a general acid/base catalyst in the enzyme.

published proceedings

  • ACS Chem Biol

author list (cited authors)

  • Sharma, V., Wang, Y., & Liu, W. R.

citation count

  • 15

complete list of authors

  • Sharma, Vangmayee||Wang, Yane-Shih||Liu, Wenshe R

publication date

  • December 2016