A new class of cobalamin transport mutants (btuF) provides genetic evidence for a periplasmic binding protein in Salmonella typhimurium.
نویسندگان
چکیده
No periplasmic binding protein has been demonstrated for the ATP-binding cassette (ABC)-type cobalamin transporter BtuCD. New mutations (btuF) are described that affect inner-membrane transport. The BtuF protein has a signal sequence and resembles the periplasmic binding proteins of several other ABC transporters.
منابع مشابه
Identification of the periplasmic cobalamin-binding protein BtuF of Escherichia coli.
Cells of Escherichia coli take up vitamin B(12) (cyano-cobalamin [CN-Cbl]) and iron chelates by use of sequential active transport processes. Transport of CN-Cbl across the outer membrane and its accumulation in the periplasm is mediated by the TonB-dependent transporter BtuB. Transport across the cytoplasmic membrane (CM) requires the BtuC and BtuD proteins, which are most related in sequence ...
متن کاملConformational Change of a Tryptophan Residue in BtuF Facilitates Binding and Transport of Cobinamide by the Vitamin B12 Transporter BtuCD-F
BtuCD-F is an ABC transporter that mediates cobalamin uptake into Escherichia coli. Early in vivo data suggested that BtuCD-F might also be involved in the uptake of cobinamide, a cobalamin precursor. However, neither was it demonstrated that BtuCD-F indeed transports cobinamide, nor was the structural basis of its recognition known. We synthesized radiolabeled cyano-cobinamide and demonstrated...
متن کاملEvidence that the CysG protein catalyzes the first reaction specific to B12 synthesis in Salmonella typhimurium, insertion of cobalt.
The cysG gene of Salmonella typhimurium is involved in synthesis of both cobalamin (B12) and siroheme (a cofactor required for SO3(2-) and NO2(2-) reductases). The failure to reduce SO3(2-) leads to cysteine auxotrophy, for which the enzyme is named. Although Escherichia coli does not synthesize B12 de novo, it possesses a very similar CysG enzyme which has been shown to catalyze two methylatio...
متن کاملTransport of 5-aminolevulinic acid by the dipeptide permease in Salmonella typhimurium.
In a previous search for mutants of Salmonella typhimurium that are defective in heme synthesis, one class that is apparently defective in 5-aminolevulinic acid (ALA) uptake (alu) was found. Here, I describe the characterization of these mutations. The mutations all map to a single locus near 77.5 min on the genetic map, which is transcribed counterclockwise. Nutritional tests, genetic and phys...
متن کاملGenetic and physiological classification of periplasmic-leaky mutants of Salmonella typhimurium.
Mutants of Salmonella typhimurium that leaked periplasmic proteins were isolated. Four classes of mutants were identified by their increased sensitivity to dyes, detergents, or antibiotics. Conjugation studies indicated that representatives of two classes mapped in the proA-galE region of the Salmonella chromosome and two in the cysI-argE region. According to their bacteriophage sensitivity pat...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of bacteriology
دوره 181 17 شماره
صفحات -
تاریخ انتشار 1999