title: Cloning and transcriptional analysis of the Thermoanaerobacter ethanolicus strain 39E maltose ABC transport system.
abstract: Thermoanaerobacter ethanolicus strain 39E is a Gram-positive thermophile that converts sugars resulting from plant carbohydrate polymer degradation into ethanol. A putative maltose ATP-binding cassette (ABC) transport operon was isolated with genes encoding for the integral membrane components (malF and malG); the ATP-binding protein (malK); and a partial gene for the maltose-binding protein (malE). This operon is unlike most other maltose transport operons, which do not contain a contiguous malK gene. Sequence analysis showed that the individual genes in the putative operon possessed a considerable range of similarities to their respective homologs in other eubacteria and archaea. MalK had 52% amino-acid identity and over 70% similarity with its homolog from the archaeon Thermococcus litoralis, while the membrane components and binding protein exhibited much less similarity with a range of other thermophilic eubacteria. Transcript was not detected in maltose-, glucose-, or xylose-grown cells using Northern blotting, but RT-PCR showed that malFGK were expressed in cells grown on maltose or xylose. Based on these results, the strain 39E maltose operon may be subject to glucose catabolite repression.
authors.affiliation: 212 W.P. Garrigus Building, Department of Animal Sciences, University of Kentucky, Lexington, KY 40546-5318, USA.
authors.forename: Chris R
authors.initials: CR
authors.lastname: Jones
authors.forename: Myrna
authors.initials: M
authors.lastname: Ray
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Strobel
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003013:Clostridium / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers; D005798:Genes, Bacterial; D008320:Maltose / Q000378:metabolism*; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D018528:ATP-Binding Cassette Transporters; D017931:DNA Primers; D008320:Maltose