title: A mgl-like operon in Treponema pallidum, the syphilis spirochete.
abstract: A 38-kDa lipoprotein of Treponema pallidum subsp. pallidum (T. pallidum), the syphilis spirochete, previously was identified as a putative homolog of E. coli MglB [Becker et al. (1994) Infect. Immun. 62, 1381-1391]. In the present study, genome walking in regions adjacent to the T. pallidum 38-kDa lipoprotein gene has identified three contiguous genes (tp-mglB [formerly tpp38], tp-mglA, and tp-mglC) which appear to comprise a mgl-like operon in T. pallidum. A prominent transcript corresponding to tp-mglB, the first gene of the operon which encodes the carbohydrate receptor, is synthesized by T. pallidum along with lesser abundant transcript(s) corresponding to the entire T. pallidum mgl operon. An active promoter 135 bp upstream of tp-mglB is believed to direct mRNA synthesis for the operon. This is the first membrane protein-encoding operon of T. pallidum for which a putative function (glucose import) has been assigned. Furthermore, by analogy with E. coli MglB which interacts with the sensory transducer Trg to induce a chemotactic response, it is possible that T. pallidum also contains a homolog of E. coli Trg or other methyl-accepting chemotaxis proteins. The existence of a mgl operon in T. pallidum thus may have important implications with respect to T. pallidum survival, tissue dissemination, and sensory transduction during virulence expression.
authors.affiliation: Department of Microbiology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
authors.forename: S F
authors.initials: SF
authors.lastname: Porcella
authors.forename: T G
authors.initials: TG
authors.lastname: Popova
authors.forename: K E
authors.initials: KE
authors.lastname: Hagman
authors.forename: C W
authors.initials: CW
authors.lastname: Penn
authors.forename: J D
authors.initials: JD
authors.lastname: Radolf
authors.forename: M V
authors.initials: MV
authors.lastname: Norgard
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics; D004269:DNA, Bacterial; D008562:Membrane Glycoproteins / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D005810:Multigene Family; D009876:Operon; D033902:Periplasmic Binding Proteins; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014210:Treponema pallidum / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C075401:MglC protein, bacteria; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D012333:RNA, Messenger; C023550:galactose-binding protein; C071728:MglA protein, Myxococcus xanthus