ISSN:
1617-4623
Keywords:
l-sorbose PTS
;
sorFBAM
;
Klebsiella pneumoniae
;
New PTS family
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract We have cloned a 3.4 kb DNA fragment from the chromosome of Klebsiella pneumoniae that codes for a phosphoenolpyruvate-dependent l-sorbose: phosphotransferase system (PTS). The cloned fragment was sequenced and four open reading frames coding for 135 (sorF), 164 (sorB), 266 (sorA) and 274 (sorM) amino acids, respectively, were found. The corresponding proteins could be detected in a T7 overexpression system, which yielded molecular masses of about 14000 for SorF, 19000 for SorB, 25000 for SorA and 27000 for SorM. SorF and SorB have all the characteristics of soluble and intracellular proteins in accordance with their functions as EIIASor and EIIBSor domains of the l-sorbose PTS. SorA and SorM, by contrast, are strongly hydrophobic, membrane-bound proteins with two to five putative transmembrane helices that alternate with a series of hydrophilic loops. They correspond to domains EIICSor and EIIDSor. The four proteins of the l-sorbose PTS resemble closely (27%–60%) the four subunits of a d-fructose PTS (EIIALev, EIIBLev, EIICLev, and EIIDLev) from Bacillus subtilis and the three subunits of the d-mannose PTS (EIIA,BMan, EIICMan, and EIIDMan) from Escherichia coli K-12. The three systems constitute a new PTS family, and sequence comparisons revealed highly conserved structures for the membranebound proteins. A consensus sequence for the membrane proteins was used to postulate a model for their integration into the membrane.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00298968
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