| Comments |
P.1297 left column bottom paragraph: "The overall abundances of chemotaxis signaling proteins (Che proteins and chemoreceptors) are variable across E. coli strains and growth conditions, but relative proportions are well conserved (ref 16). Strikingly, these proteins are more highly expressed in minimal medium than in rich medium (ref 16). When the abundances of chemotaxis signaling proteins were varied in a concerted fashion (ref 15), the chemotactic efficiency of cells (measured by a swarm assay) was found to increase sharply up to wild-type abundance, and then to continue increasing much more gradually while progressively leveling off. Here, to mimic the experiment of Kollmann et al. (ref 15), [investigators] vary the abundances of CheA, CheY, CheZ, CheB, and CheR while keeping their proportions and the FliM abundance fixed, as in Table S2. ([They] checked that varying the abundance of FliM in a concerted fashion with the other abundances does not affect [their] conclusions.) Solving [their] pathway model (Eqs. 1–11) in the adapted steady state, [they] find that when protein abundances are increased, [CheY-P] and ψ both increase sharply up to about reference abundances, and the increase then progressively levels off ( Fig. 4A). [Their] reference abundances (onefold in Fig. 4) correspond to those measured by Li and Hazelbauer (ref 16 BNID 107850) for strain RP437 in rich medium (see Materials and Methods and Table S2)." |