GenePage for the chbB gene of Escherichia coli K-12

Primary Gene Name: chbB
EcoGene Accession Number: EG10140
K-12 Gene Accession Number: ECK1736
MG1655 Gene Identifier: b1738
Gene Name Mnemonic: Chitobiose
Alternate Gene Symbols: celA
Description: N,N'-diacetylchitobiose utilization, enzyme IIB(Chb) of the PTS transport system
  # bp Upstream # bp Downstream
MW: 11426.54 ---------106 aa Pre-Run BlastP UniProt
Pre-Run BlastP NR+Env
Left End: 1821299
Left Intergenic Region

Name: chbC_chbB

Length: 84 bp gap

Orientation: Codirectional-

Left_end: 1821215

Right_end: 1821298

Centisome: 39.24

Genomic Address
Counterclockwise
Minute or Centisome (%) = 39.24
Right End: 1821619
Right Intergenic Region

Name: chbB_osmE

Length: 298 bp gap

Orientation: Codirectional-

Left_end: 1821620

Right_end: 1821917

Centisome: 39.25

The chb operon is induced by N,N'-diacetylchitobiose. The chb operon was previously thought to encode a cryptic cel operon for a cellobiose degradation system. The Cel+ phenotype is due to mutations making expression chitobiose-independent, but a fully induced operon did not support growth on cellobiose, implying a mutation altering the substrate specificity is needed; several candidate mutations were noted in Genbank, but not proven to alter the specificity of the system (Keyhani, 1997). In contrast, a later study claim that mutations making the operon expression high-level constitutive by chbR and nagC mutations are sufficient for the Cel+ phenotype and that no mutations altering substrate specificity are required (Kachroo, 2007). The chbBC intergenic region contains an RNA decoy (trap-mRNA) which is antisense to the chiX(micM) sRNA; induction of the chb operon leads to chiX(micM) degradation and consequently to chiP induction as chiX(micM) repression is relieved (Overgaard, 2009). In Salmonella, chiX(micM) is also inactivated by the chbBC intergenic region, which in Salmonella (and possibly in E. coli also) is processed by RNase E to a ~3000 bp fragment (Figuera-Bossi (2009).

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BamHI EcoRI HindIII