Crystal Structure of Hypothetical Fructose-Specific EIIB from Escherichia coli
- 주제(키워드) frwD , fructose specific enzyme EIIB , functional cysteine , PTS permease , PTS system , X-ray crystallography
- 발행기관 KOREAN SOC MOLECULAR & CELLULAR BIOLOGY
- 발행년도 2016
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000129900
- 본문언어 영어
- Published As http://dx.doi.org/10.14348/molcells.2016.0055
초록/요약
We have solved the crystal structure of a predicted fructose-specific enzyme IIBfruc from Escherichia coli (EcEIIB(fruc)) involved in the phosphoenolpyruvate-carbohydrate phosphotransferase system transferring carbohydrates across the cytoplasmic membrane. EcEIIB(fruc) belongs to a sequence family with more than 5,000 sequence homologues with 25-99% amino-acid sequence identity. It reveals a conventional Rossmann-like alpha-beta-alpha sandwich fold with a unique beta-sheet topology. Its C-terminus is longer than its closest relatives and forms an additional beta-strand whereas the shorter C-terminus is random coil in the relatives. Interestingly, its core structure is similar to that of enzyme IIBcellobiose from E. coli (EcIIB(cel)) transferring a phosphate moiety. In the active site of the closest EcEIIB(fruc) homologues, a unique motif CXXGXAHT comprising a P-loop like architecture including a histidine residue is found. The conserved cysteine on this loop may be deprotonated to act as a nucleophile similar to that of EcIIB(cel). The conserved histidine residue is presumed to bind the negatively charged phosphate. Therefore, we propose that the catalytic mechanism of EcEIIB(fruc) is similar to that of EcIIB(cel) transferring phosphoryl moiety to a specific carbohydrate.
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