HPr: a model protein

Histidine-containing protein (HPr) is a central component of the bacterial phosphoenolpyruvate: sugar phosphotransferase system (PTS). This brief review covers recent structure–function studies on the active center of this protein: the role of the active center residues in phosphotransfer; the residues contributing to the phosphohydrolysis properties of HPr; and the contribution residues in HPr make to the pKaof the transiently phosphorylated active-site residue, His 15. As well, the potential for HPr to be used as a model protein for studying problems not directly associated with its function in the PTS is discussed.Key words: phosphoenolpyruvate: sugar phosphotransferase system, histidine-containing protein, active center, structure–function, model protein.

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Role of the conserved active site residue tryptophan-24 of human dihydrofolate reductase as revealed by mutagenesis

Biochemistry ◽

10.1021/bi00219a038 ◽

1991 ◽

Vol 30 (5) ◽

pp. 1432-1440 ◽

Cited By ~ 14

Author(s):

William A. Beard ◽

James R. Appleman ◽

Shaoming Huang ◽

Tavner J. Delcamp ◽

James H. Freisheim ◽

...

Keyword(s):

Dihydrofolate Reductase ◽

Active Site ◽

Active Site Residue ◽

Human Dihydrofolate Reductase

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Functional role of a non-active site residue Trp23 on the enzyme activity of Escherichia coli thioesterase I/protease I/lysophospholipase L1

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics ◽

10.1016/j.bbapap.2009.06.008 ◽

2009 ◽

Vol 1794 (10) ◽

pp. 1467-1473 ◽

Cited By ~ 11

Author(s):

Li-Chiun Lee ◽

Yi-Li Chou ◽

Hong-Hwa Chen ◽

Ya-Lin Lee ◽

Jei-Fu Shaw

Keyword(s):

Escherichia Coli ◽

Enzyme Activity ◽

Active Site ◽

Functional Role ◽

Active Site Residue

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The key role of a non-active-site residue Met148 on the catalytic efficiency of meta-cleavage product hydrolase BphD

Applied Microbiology and Biotechnology ◽

10.1007/s00253-013-4814-0 ◽

2013 ◽

Vol 97 (24) ◽

pp. 10399-10411 ◽

Cited By ~ 11

Author(s):

Hao Zhou ◽

Yuanyuan Qu ◽

Chunlei Kong ◽

E. Shen ◽

Jingwei Wang ◽

...

Keyword(s):

Active Site ◽

Catalytic Efficiency ◽

Cleavage Product ◽

Active Site Residue

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Analysis of the Role of the Active Site Residue Arg98 in the Flavoprotein Tryptophan 2-Monooxygenase, a Member of thel-Amino Oxidase Family†

Biochemistry ◽

10.1021/bi035299n ◽

2003 ◽

Vol 42 (47) ◽

pp. 13826-13832 ◽

Cited By ~ 19

Author(s):

Pablo Sobrado ◽

Paul F. Fitzpatrick

Keyword(s):

Active Site ◽

Active Site Residue ◽

Amino Oxidase

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Structure-Based Mechanism for Early PLP-Mediated Steps of Rabbit Cytosolic Serine Hydroxymethyltransferase Reaction

BioMed Research International ◽

10.1155/2013/458571 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 10

Author(s):

Martino L. Di Salvo ◽

J. Neel Scarsdale ◽

Galina Kazanina ◽

Roberto Contestabile ◽

Verne Schirch ◽

...

Keyword(s):

Crystal Structures ◽

Active Site ◽

Catalytic Mechanism ◽

Serine Hydroxymethyltransferase ◽

Active Site Residue ◽

Wild Type ◽

Hydroxymethyl Group ◽

New Energy ◽

Mutant Forms

Serine hydroxymethyltransferase catalyzes the reversible interconversion of L-serine and glycine with transfer of one-carbon groups to and from tetrahydrofolate. Active site residue Thr254 is known to be involved in the transaldimination reaction, a crucial step in the catalytic mechanism of all pyridoxal 5′-phosphate- (PLP-) dependent enzymes, which determines binding of substrates and release of products. In order to better understand the role of Thr254, we have expressed, characterized, and determined the crystal structures of rabbit cytosolic serine hydroxymethyltransferase T254A and T254C mutant forms, in the absence and presence of substrates. These mutants accumulate a kinetically stablegem-diamine intermediate, and their crystal structures show differences in the active site with respect to wild type. The kinetic and crystallographic data acquired with mutant enzymes permit us to infer that conversion ofgem-diamine to external aldimine is significantly slowed because intermediates are trapped into an anomalous position by a misorientation of the PLP ring, and a new energy barrier hampers the transaldimination reaction. This barrier likely arises from the loss of the stabilizing hydrogen bond between the hydroxymethyl group of Thr254 and theε-amino group of active site Lys257, which stabilizes the external aldimine intermediate in wild type SHMTs.

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