The hisB gene, found in the enterobacteria (such as E. coli), in Campylobacter jejuni and in Xylella/ Xanthomonas encodes a protein involved in catalysis of two step in histidine biosynthesis (the sixth and eight step), namely the bifunctional Imidazoleglycerol-phosphate dehydratase/ histidinol-phosphatase. [1]
The former function ( EC 4.2.1.19), found at the N-terminal, dehydrated d-erythroimidazoleglycerolphosphate to imidazoleacetolphosphate, the latter function ( EC 3.1.3.15), found at the C-terminal, dephosphorylates l-histidinolphosphate producing histidinol. [2] [3] [4]
The firth step is catalysed instead by histadinolphosphate aminotransferase (encoded by hisC) [5]
The peptide is 40.5kDa and associates to form a hexamer (unless truncated) [6]
In E. coli hisB is found on the hisGDCBHAFI operon [7]
The phosphatase activity possess a substrate ambiguity and overexpression of hisB can rescue phosphoserine phosphatase (serB) knockouts. [8]
hisB-N
hisB-C
HIS3 from Saccharomyces cerevisiae is not a fused IGP dehydratase and hisidinol phosphatase, but an IGPD only (homologous to hisB-N). Whereas HIS2 is the HP (analogous to hisB-C, called hisJ in some prokaryotes).
The hisB gene, found in the enterobacteria (such as E. coli), in Campylobacter jejuni and in Xylella/ Xanthomonas encodes a protein involved in catalysis of two step in histidine biosynthesis (the sixth and eight step), namely the bifunctional Imidazoleglycerol-phosphate dehydratase/ histidinol-phosphatase. [1]
The former function ( EC 4.2.1.19), found at the N-terminal, dehydrated d-erythroimidazoleglycerolphosphate to imidazoleacetolphosphate, the latter function ( EC 3.1.3.15), found at the C-terminal, dephosphorylates l-histidinolphosphate producing histidinol. [2] [3] [4]
The firth step is catalysed instead by histadinolphosphate aminotransferase (encoded by hisC) [5]
The peptide is 40.5kDa and associates to form a hexamer (unless truncated) [6]
In E. coli hisB is found on the hisGDCBHAFI operon [7]
The phosphatase activity possess a substrate ambiguity and overexpression of hisB can rescue phosphoserine phosphatase (serB) knockouts. [8]
hisB-N
hisB-C
HIS3 from Saccharomyces cerevisiae is not a fused IGP dehydratase and hisidinol phosphatase, but an IGPD only (homologous to hisB-N). Whereas HIS2 is the HP (analogous to hisB-C, called hisJ in some prokaryotes).