Disease relevance of hemC

• Porphobilinogen deaminase, the product of the hemC locus in Escherichia coli K12, catalyses the tetrapolymerisation of porphobilinogen (PBG) into the hydroxymethylbilane, preuroporphyrinogen [1].
• The Chlorobium gene was confirmed to be the porphobilinogen deaminase gene, and complete sequence of the structural gene was obtained [2].
• This mutation could be complemented with a plasmid harboring the hemE gene of Synechococcus [3].
• The porphobilinogen deaminase encoded by the Clostridium josui hemC gene was purified from a recombinant Escherichia coli strain and its properties were characterized [4].
• The region downstream of the dnaX AUG, which is important for efficient translation, exhibits homology with the corresponding region from the Caulobacter hemE gene adjacent to the replication origin [5].

High impact information on hemC

• Structure of porphobilinogen deaminase reveals a flexible multidomain polymerase with a single catalytic site [6].
• The sequence of hemC, hemD and two additional E. coli genes [7].
• The hemC locus has been subcloned from the Clarke and Carbon plasmid pLC41-4 [1].
• The structural gene for hemC is located within a 942bp sequence encoding the monomeric PBG deaminase, molecular weight 33,857 [1].
• Nucleotide sequence of the hemC locus encoding porphobilinogen deaminase of Escherichia coli K12 [1].

Chemical compound and disease context of hemC

• An Escherichia coli heme-requiring, heme-permeable mutant had no detectable 5-aminolevulinate dehydratase or porphobilinogen deaminase activities [8].
• Investigation into the nature of substrate binding to the dipyrromethane cofactor of Escherichia coli porphobilinogen deaminase [9].
• Mutagenesis of arginine residues in the catalytic cleft of Escherichia coli porphobilinogen deaminase that affects dipyrromethane cofactor assembly and tetrapyrrole chain initiation and elongation [10].
• Hydroxymethylbilane synthase (porphobilinogen deaminase) was purified to apparent homogeneity from Escherichia coli [11].

Biological context of hemC

• The third open reading frame is hemC, coding for porphobilinogen deaminase [12].
• 1. The hemD gene, encoding uroporphyrinogen III synthase, has been located adjacent to the hemC gene at 85 min on the Escherichia coli chromosome [13].
• The hemE gene was identified from amino acid sequence comparisons as encoding uroporphyrinogen III decarboxylase [14].
• Preliminary evidence for a hemEHY mRNA was obtained, and a promoter region located in front of hemE was identified [14].
• Evidence for participation of aspartate-84 as a catalytic group at the active site of porphobilinogen deaminase obtained by site-directed mutagenesis of the hemC gene from Escherichia coli [15].

Associations of hemC with chemical compounds

• The gene which complemented this mutation was cloned to a high-copy-number plasmid, and porphobilinogen deaminase activity was restored to normal levels, but the synthesis of 5-aminolevulinate dehydratase increased 20- to 30-fold [8].
• Evidence that pyridoxal phosphate modification of lysine residues (Lys-55 and Lys-59) causes inactivation of hydroxymethylbilane synthase (porphobilinogen deaminase) [16].
• Overproduction and purification of HemC (porphobilinogen deaminase) and -D (uroporphyrinogen III synthase) allowed these enzymes to be used for the in vitro synthesis of uroporphyrinogen III from porphobilinogen [17].
• Evidence that the pyrromethane cofactor of hydroxymethylbilane synthase (porphobilinogen deaminase) is bound to the protein through the sulphur atom of cysteine-242 [18].
• In addition, this construct could complement the hemE requirement of 10L2-1 as well as allow it to grow on chloramphenicol [3].

Other interactions of hemC

• Characterization of a hemA/hemE mutant of E. coli and regulation of hemE [3].
• The second mutation which was identified as hemE because it was mapped to 90.1 min. by F' and Hfr mapping and P1 transduction, accumulated uroporphyrin and had no uroporphyrinogen decarboxylase activity [3].

Analytical, diagnostic and therapeutic context of hemC

• Purification, crystallization and properties of porphobilinogen deaminase from a recombinant strain of Escherichia coli K12 [19].

References