Pathways for the utilization of N-acetyl-galactosamine and galactosamine in Escherichia coli

Autor(en): Brinkkotter, A
Kloss, H
Alpert, CA
Lengeler, JW
Stichwörter: AMINO-SUGARS; BACTERIUM VIBRIO-FURNISSII; Biochemistry & Molecular Biology; ENZYMES-II; GLUCOSAMINE-6-PHOSPHATE SYNTHASE; HIGH-LEVEL; KLEBSIELLA-PNEUMONIAE; Microbiology; MOLECULAR-CLONING; NAG REGULON; PHOSPHOTRANSFERASE SYSTEM; SUGAR-TRANSPORT
Erscheinungsdatum: 2000
Herausgeber: BLACKWELL SCIENCE LTD
Journal: MOLECULAR MICROBIOLOGY
Volumen: 37
Ausgabe: 1
Startseite: 125
Seitenende: 135
Zusammenfassung: 
Among enteric bacteria, the ability to grow on N-acetyl-galactosamine (GalNAc or Aga) and on d-galactosamine (GalN or Gam) differs. Thus, strains B, C and EC3132 of Escherichia coli are Aga(+) Gam(+) whereas E. coli K-12 is Aga(-) Gam(-), similarly to Klebsiella pneumoniae KAY2026, Klebsiella oxytoca M5a1 and Salmonella typhimurium LT2. The former strains carry a complete aga/kba gene cluster at 70.5 min of their gene map. These genes encode an Aga-specific phosphotransferase system (PTS) or IIAga (agaVWE) and a GalN-specific PTS or IIGam (agaBCD). Both PTSs belong to the mannose-sorbose family, i.e. the IIB, IIC and IID domains are encoded by different genes, and they share a IIA domain (agaF). Furthermore, the genes encode an Aga6P-deacetylase (agaA), a GalN6P deaminase (agaI), a tagatose-bisphosphate aldolase comprising two different peptides (kbaYZ) and a putative isomerase (agaS), i.e. complete pathways for the transport and degradation of both amino sugars. The genes are organized in two adjacent operons (kbaZagaVWEFA and agaS kbaYagaBCDI) and controlled by a repressor AgaR. Its gene agaR is located upstream of kbaZ, and AgaR responds to GalNAc and GalN in the medium. All Aga(-) Gam(-) strains, however, carry a deletion covering genes agaW' EF `A; consequently they lack active IIAga and IIGam PTSs, thus explaining their inability to grow on the two amino sugars. Remnants of a putative recombination site flank the deleted DNA in the various Aga(-) Gam(-) enteric bacteria. Derivatives with an Aga(+) Gam(-) phenotype can be isolated from E. coli K-12. These retain the Delta agaW' EF `A deletion and carry suppressor mutations in the gat and nag genes for galactitol and N-acetyl-glucosamine metabolism, respectively, that allow growth on Aga but not on GalN.
ISSN: 0950382X
DOI: 10.1046/j.1365-2958.2000.01969.x

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