title: Quantitative modeling of sensitivity in bacterial chemotaxis: the role of coupling among different chemoreceptor species.
abstract: We propose a general theoretical framework for modeling receptor sensitivity in bacterial chemotaxis, taking into account receptor interactions, including those among different receptor species. We show that our model can quantitatively explain the recent in vivo measurements of receptor sensitivity at different ligand concentrations for both mutant and wild-type strains. For mutant strains, our model can fit the experimental data exactly. For the wild-type cell, our model is capable of achieving high gain while having modest values of Hill coefficient for the response curves. Furthermore, the high sensitivity of the wild-type cell in our model is maintained for a wide range of ambient ligand concentrations, facilitated by near-perfect adaptation and dependence of ligand binding on receptor activity. Our study reveals the importance of coupling among different chemoreceptor species, in particular strong interactions between the aspartate (Tar) and serine (Tsr) receptors, which is crucial in explaining both the mutant and wild-type data. Predictions for the sensitivity of other mutant strains and possible improvements of our model for the wild-type cell are also discussed.
authors.affiliation: IBM T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598, USA.
authors.forename: Bernardo A
authors.initials: BA
authors.lastname: Mello
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Tu
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002628:Chemoreceptor Cells / Q000378:metabolism*; D002630:Chemotactic Factors / Q000378:metabolism*; D002633:Chemotaxis / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008956:Models, Chemical; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002630:Chemotactic Factors; D029968:Escherichia coli Proteins; D008024:Ligands; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; C057331:Tar protein, E coli; C057635:Tsr protein, Bacteria; C069656:CheB protein, Bacteria; D008780:Methyltransferases; C038706:chemotaxis methyltransferase