Direct visualization of Escherichia coli chemotaxis receptor arrays using cryo-electron microscopy -- Zhang et al. 104 (10): 3777 Data Supplement - HTML Page - index.htslp -- Proceedings of the National Academy of Sciences

Zhang et al. 10.1073/pnas.0610106104.

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SI Figure 6
SI Figure 7
SI Figure 8

SI Figure 6

Fig. 6. Comparison of the chemotaxis deletion mutant RP3098 with wild-type RP437. (A) Cryoprojection image of the polar region RP3098, a strain that does not express chemoreceptors, CheA, or CheW. (B) Cryoprojection image of wild-type RP437 (same as in Fig. 1A).

SI Figure 7

Fig. 7. Variation in chemoreceptor array size and location. (A) Histogram of chemoreceptor arrays observed in RP437 Escherichia coli cells cultured in LB, TB, or H1 medium. The ordinate represents the percentage of cells in a given population that displayed receptor arrays in the indicated size range, in steps of 100 nm. The sum over all of the observed percentages for each size range reflects the total percentage of cells displaying detectable receptor arrays for each growth condition. Because the receptor arrays rarely span the entire polar region, the percent shown only reflects those cells in which the array is predominantly oriented on its edge and does not account for arrays that are located on the top or bottom faces of the cell. Array lengths were measured along the geodesic of the membrane surface. (B) Expression profiles for Tsr, CheA, and CheW demonstrating variation in chemoreceptor array components in different growth media.

SI Figure 8

Fig. 8. Rescue of the chemotaxis phenotype in cells overexpressing Tsr by the overexpression of CheA and CheW. (A) Swarming and corresponding protein expression levels for chemoreceptor deletion mutant (UU1250) complemented with both a Tsr-inducible plasmid (pJC3) and CheA/CheW-inducible plasmid (pPM23) to enable overexpression of CheA and CheW above wild-type levels. RP437/pCJ30/pKG116 and UU1250/pCJ30/pKG116 were used as positive (+) and negative (-) controls, respectively. Induction of cells with 50 mM isopropyl b-D-thiogalactopyranosidase (IPTG) led to a decrease in swarming motility similar to observed levels shown in Fig. 3c. However, as the amount of CheA and CheW was increased, both swarming ability and chemoreceptor array formation were restored. (B) A representative cryoprojection image of an intact UU1250/pJC3/pPM23 cell induced with 50 mM IPTG and 1.0 mM Na-S demonstrating rescue of chemoreceptor array formation.