GenePage for the hiuH gene of Escherichia coli K-12

Primary Gene Name: hiuH
EcoGene Accession Number: EG14046
K-12 Gene Accession Number: ECK1966
MG1655 Gene Identifier: b1970
Gene Name Mnemonic: HIUHase
Alternate Gene Symbols: yedX
Description: Hydroxyisourate hydrolase; HIU hydrolase, HIUHase; periplasmic transthyretin-like protein (TLP); EcTRP; tetrameric, metal-binding; unrelated to soybean HIUHase
  # bp Upstream # bp Downstream
MW: 15459.61 ---------137 aa Pre-Run BlastP UniProt
Pre-Run BlastP NR+Env
Left End: 2038956
Left Intergenic Region

Name: yedW_hiuH

Length: 132 bp gap

Orientation: Divergent

Left_end: 2038824

Right_end: 2038955

Centisome: 43.92

Genomic Address
Minute or Centisome (%) = 43.93
Right End: 2039369
Right Intergenic Region

Name: hiuH_yedY

Length: 108 bp gap

Orientation: Codirectional+

Left_end: 2039370

Right_end: 2039477

Centisome: 43.94

Purified E. coli HiuH(YedX) hydrolyzes 5-hydroxyisourate producing both allantoin and the intermediate 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) which will spontaneously decay into a racemic mixture of R- and S-allantoin but AllB allantoinase metabolizes S-allantoin only, so HiuH may also have OHCU decarboxylase activity (Lee, 2005; Hennebry, 2006). The E. coli K-12 genome does not encode an OHCU decarboxylase (COG3195) homolog. E. coli can convert xanthine to allantoin, although less efficiently than K. pneumoniae; HiuH(YedX) might participate in purine catabolism by helping to degrade the uric acid produced by xanthine dehydrogenase (Xi, 2000). It has been suggested that the lack of uricase enzyme activity might be partially compensated for by a spontaneous reaction of uric acid acting as an antioxidant in the periplasm resulting in a non-enzymatic production of 5-hydroxyisourate and that HiuH might protect from free radicals (Hennebry, 2006). The HIUHase family has a C -terminal YRGS conserved motif. Purified E. coli HiuH(YedX) can be induced to form fibrils with stirring or heat (Santos, 2008; Lundberg, 2009). Cleavage of the 23 aa signal peptide and the periplasmic localization of HiuH(YedX) have been experimentally verified (Mitchell, R., Hus, N. and Rudd, K.E., unpublished results, 1999). PDB: 2IGL citation: Purification and structure determination of YedX, a transthyretin-related protein from Escherichia coli, Zuo, Y., Ballanco, J., Shah, J., Wang, Y., Rivera, S., Ragan, T.J., Hernandez, G., Nelersa, C.M., Mitchell, R., Rudd, K.E., and Malhotra, A., unpublished, 2006).

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