Related Experiment Video

Updated: Sep 20, 2026

Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers
13:14

Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers

Published on: August 22, 2014

Ammonium (methylammonium) transport by Klebsiella pneumoniae

D Kleiner

    Biochimica Et Biophysica Acta
    |June 28, 1982
    PubMed

    Insights

    Klebsiella pneumoniae utilizes a specific transport system to accumulate methylammonium, driven by proton motive force. This system

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Biochemistry

    Background:

    • Klebsiella pneumoniae possesses a transport system enabling methylammonium accumulation.
    • This system exhibits characteristics like energy dependence, saturation kinetics, and a specific pH optimum around 6.8.

    Purpose of the Study:

    • To elucidate the characteristics and natural substrate of the methylammonium transport system in Klebsiella pneumoniae.
    • To investigate the energy source and genetic regulation of this transport system.

    Main Methods:

    • Characterization of methylammonium transport kinetics, including Km and Vmax.
    • Competitive inhibition studies using ammonium to determine the substrate specificity.
    • Analysis of transport under varying pH and energy conditions.
    • Genetic analysis of transport system regulation using mutants.

    Main Results:

    • Methylammonium transport shows saturation kinetics (apparent Km = 100 microM) and is competitively inhibited by ammonium (apparent Ki = 7 microM).
    • The low Ki for ammonium and inability of methylammonium to serve as a nitrogen source indicate ammonium as the natural substrate.
    • Uphill transport is energized by the protonmotive force, likely the membrane potential.
    • The transport system is genetically regulated, repressed by amino acids and ammonium, consistent with nitrogen control mechanisms.

    Conclusions:

    • Klebsiella pneumoniae employs a high-affinity ammonium transport system that also transports methylammonium.
    • The transport is driven by the protonmotive force and subject to nitrogen metabolic regulation.
    • Understanding this system provides insights into nutrient acquisition and regulation in bacteria.

    More Related Videos

    Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane07:38

    Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

    Published on: March 30, 2015

    Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles13:16

    Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles

    Published on: December 31, 2019

    Related Concept Videos

    ABC Transporters: Exporter01:31

    ABC Transporters: Exporter

    ATP-binding cassette or ABC transporter is the largest superfamily of integral membrane proteins. The transporters have transmembrane-binding domains (TMDs) and nucleotide-binding domains (NBDs). The TMDs are specific to their substrates, whereas the NBDs are similar to engines that complete ATP hydrolysis to complete the substrate transport. They can be full transporters consisting of two TMDs and NBDs, half transporters with one TMD and NBD, while some encoded with a single TMD or NBD are...
    ABC Transporters: Importer01:27

    ABC Transporters: Importer

    ATP-binding cassette or ABC transporters are a class of ATP-driven pumps that hydrolyze ATP to move solutes across the membrane. They can be grouped into importers and exporters. While exporters are present in all domains of life, importers exist only in bacteria and some plants.
    In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
    Transcellular Transport of Solutes01:23

    Transcellular Transport of Solutes

    Transcellular transport of solutes is the movement of substances like monosaccharides and amino acids through polarized cells. This transport mechanism is primarily seen in epithelial and endothelial cells aided by membrane transport proteins such as channels and transporters. The tight junctions between these cells confine the membrane proteins to the two sides of the cell. The epithelial cells have distinct apical and basolateral domains. In contrast, the endothelial cells show the luminal...
    Drug Elimination by Renal Route: Tubular Secretion01:15

    Drug Elimination by Renal Route: Tubular Secretion

    Once the process of glomerular filtration is completed, blood carrying unfiltered drug molecules traverses through efferent arterioles and makes its way into the peritubular capillaries in the proximal tubule. A variety of carriers play a pivotal role in actively secreting drugs from these peritubular capillaries into the tubular fluid. The organic anion transporter transfers acidic drugs, against an electrochemical gradient, from the peritubular capillaries into the renal tubule cells and...
    Reabsorption and Secretion in the PCT01:28

    Reabsorption and Secretion in the PCT

    The Proximal Convoluted Tubule, or PCT, plays a pivotal role in the body's filtration system. They are primarily responsible for reabsorbing solutes and water from the filtered fluid produced by the glomeruli. Most of the filtered water, ions, and organic solutes such as glucose and amino acids are reabsorbed by the PCT.
    Transport mechanisms involving sodium ions (Na+) contribute significantly to solute reabsorption. These mechanisms include symport and antiport processes.
    A key example is the...
    Pore Transport and Ion-Pair Transport01:17

    Pore Transport and Ion-Pair Transport

    Pore transport and ion-pair formation are critical mechanisms for the absorption and distribution of drugs in the body.
    Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited  but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...