title: A novel glutamate transport system in poly(γ-glutamic acid)-producing strain Bacillus subtilis CGMCC 0833.
abstract: Bacillus subtilis CGMCC 0833 is a poly(γ-glutamic acid) (γ-PGA)-producing strain. It has the capacity to tolerate high concentration of extracellular glutamate and to utilize glutamate actively. Such a high uptake capacity was owing to an active transport system for glutamate. Therefore, a specific transport system for L-glutamate has been observed in this strain. It was a novel transport process in which glutamate was symported with at least two protons, and an inward-directed sodium gradient had no stimulatory effect on it. K(m) and V(m) for glutamate transport were estimated to be 67 μM and 152 nmol⁻¹ min⁻¹ mg⁻¹ of protein, respectively. The transport system showed structural specificity and stereospecificity and was strongly dependent on extracellular pH. Moreover, it could be stimulated by Mg²⁺, NH₄⁺, and Ca²⁺. In addition, the glutamate transporter in this strain was studied at the molecular level. As there was no important mutation of the transporter protein, it appeared that the differences of glutamate transporter properties between this strain and other B. subtilis strains were not due to the differences of the amino acid sequence and the structure of transporter protein. This is the first extensive report on the properties of glutamate transport system in γ-PGA-producing strain.
authors: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing University of Technology, Nanjing 210009, China.
authors: Qun
authors: Q
authors: Wu
authors: Hong
authors: H
authors: Xu
authors: Dan
authors: D
authors: Zhang
authors: Pingkai
authors: P
authors: Ouyang
mesh_terms: D027322:Amino Acid Transport System X-AG / Q000235:genetics* / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002412:Cations / Q000378:metabolism / Q000494:pharmacology; D003001:Cloning, Molecular; D018698:Glutamic Acid / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014634:Valinomycin / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
chemical_list: D027322:Amino Acid Transport System X-AG; D001426:Bacterial Proteins; D002412:Cations; C511775:poly(gamma-glutamic acid); D014634:Valinomycin; D011099:Polyglutamic Acid; D018698:Glutamic Acid; D014638:Vanadates; D000641:Ammonia; D008274:Magnesium; D002118:Calcium